New Polylactic Acid Composites Reinforced with Artichoke Fibers

In this work, artichoke fibers were used for the first time to prepare poly(lactic acid) (PLA)-based biocomposites. In particular, two PLA/artichoke composites with the same fiber loading (10% w/w) were prepared by the film-stacking method: the first one (UNID) reinforced with unidirectional long artichoke fibers, the second one (RANDOM) reinforced by randomly-oriented long artichoke fibers. Both composites were mechanically characterized in tensile mode by quasi-static and dynamic mechanical tests. The morphology of the fracture surfaces was analyzed through scanning electron microscopy (SEM). Moreover, a theoretical model, i.e., Hill's method, was used to fit the experimental Young's modu…

Effect of temperature on the release of carvacrol and cinnamaldehyde incorporated into polymeric systems to control growth and biofilms ofEscherichia coliandStaphylococcus aureus

This study assessed the effect of temperature on the release of essential oil components incorporated by melt compounding into polymeric films. Specifically, polyethylene-co-vinylacetate (EVA) films containing carvacrol (CAR) and cinnamaldehyde (ALD), alone and in combination, were prepared and their surface and mechanical properties and antibacterial and anti-biofilm activity against Escherichia coli and Staphylococcus aureus were evaluated. The addition of ALD and CAR did not provoke variation in the surface morphology of EVA and allowed their delivery. At 37°C, films containing CAR, ALD or their combination (25+75%) were found to have the strongest bactericidal effect, whereas at lower t…

Compatibilization of polymer blends by using a cyclophosphazene additive

Development and characterization of antimicrobial PCL fibres for surgical suture applications

Role of oxyegen on rheological response of polyethylene–clay nanocomposites to annealing

Bi-layer PCL/PLA scaffold prepared by melt for interface tissue engineering

The development of porous multilayer devices allow controlling chemical, physical and mechanical properties by tuning the properties of each single layer. For instance, this feature is of main concern for the production of porous devices designed to regenerate diseased zones at the interface of tissue presenting intrinsic anisotropic structures that gradually change from one tissue to another. In this context, synthetic biodegradable polymers commonly used biomedical applications include polylactic acid (PLA) and polycaprolactone (PCL). In this work, a novel bi-layered multiphasic scaffold (BLS) is presented. It is composed by a PLA-layer presenting pore size in the range of 90-110 μm while…

Effect of Graphene Nanoplatelets on the Physical and Antimicrobial Properties of Biopolymer-Based Nanocomposites

In this work, biopolymer-based nanocomposites with antimicrobial properties were prepared via melt-compounding. In particular, graphene nanoplatelets (GnPs) as fillers and an antibiotic, i.e., ciprofloxacin (CFX), as biocide were incorporated in a commercial biodegradable polymer blend of poly(lactic acid) (PLA) and a copolyester (BioFlex®). The prepared materials were characterized by scanning electron microscopy (SEM), and rheological and mechanical measurements. Moreover, the effect of GnPs on the antimicrobial properties and release kinetics of CFX was evaluated. The results indicated that the incorporation of GnPs increased the stiffness of the biopolymeric matrix and allowed for the t…

Polyethylene–clay nanocomposite: Effect of annealing under different atmospheres

Fibre antimicrobiche per applicazioni chirurgiche

Fabrication of Bismuth Absorber Arrays for NTD-Ge Hard X-ray Microcalorimeters

The high-spectral-resolution detection of hard X-rays (E > 20 keV) is a challenging and nearly unexplored area in space astrophysics. Traditionally hard X-ray detectors present moderate spectral resolutions, although few tens of eV one could open new frontiers in the study of nuclear processes and high-temperature plasma dynamics in energetic processes. This can be achieved by using cryogenic microcalorimeters. Within a research activity aimed at developing arrays of neutron transmutation-doped germanium (NTD-Ge) microcalorimeters for the high-spectral-resolution detection (about 50 eV@60 keV) of hard X-rays (20 keV < E<100 keV), we developed an electroplating process to fabricate …

Preparation of three-layered porous PLA/PEG scaffold: relationship between morphology, mechanical behavior and cell permeability.

Interface tissue engineering (ITE) is used to repair or regenerate interface living tissue such as for instance bone and cartilage. This kind of tissues present natural different properties from a biological and mechanical point of view. With the aim to imitating the natural gradient occurring in the bone-cartilage tissue, several technologies and methods have been proposed over recent years in order to develop polymeric functionally graded scaffolds (FGS). In this study three-layered scaffolds with a pore size gradient were developed by melt mixing polylactic acid (PLA) and two water-soluble porogen agents: sodium chloride (NaCl) and polyethylene glycol (PEG). Pore dimensions were controll…

Prediction of the morphology of polymer-clay nanocomposites

Abstract Polymer nanocomposites have continually attracted increasing interest over the last decade, due to significant improvements they can offer compared to neat polymer matrices. However, the final morphology of a nanocomposite, determined by several variables, can significantly influence the macroscopic properties of the final product. Therefore, it is important to study the interactions between processing, morphology, structure and rheological properties, and the suitability of existing models in order to predict the system's behaviour with change of the main processing variables. In this work, the applicability of a predictive theory based on the Wu model was formulated and proposed …

Improvement of the photo-stability of nanocomposite based LDPE/EVA films

Functional biopolymer-based nanocomposites incorporating graphene nanoplatelets

The effectiveness of the antimicrobial activity over time is mainly determined by the release rate of the antimicrobial compounds. The rate of release depends on different factors such as preparation method, environmental conditions, interactions between antimicrobial and matrix. In this regard, nanoparticles can potentially be used to control the release of antimicrobial agents. Moreover, it is well known that the incorporation of nano-sized fillers into a biopolymeric matrix is an effective way to improve its properties. Aim of this work was to prepare and characterize biopolymer-based nanocomposites with antimicrobial properties. In particular, graphene nanoplatelets (GnPs) as fillers an…

Control of biofilm formation by poly-ethylene-co-vinyl acetate films incorporating nisin.

The aim of this study was to evaluate the effect of poly-ethylene-co-vinyl acetate (EVA) films incorporating different concentrations (0.1%, 0.5% and 1%) of nisin on the biofilm-forming ability of Listeria monocytogenes ATCC 7644, Staphylococcus aureus 815 and Staphylococ-cus epidermidis ATCC 35984. Nisin was incorporated into two grades of EVA (EVA14 and EVA28) in the melt during a common film-blowing operation. The efficacy of EVA/nisin films was evaluated by biofilm biomass measurements and Live/Dead staining in combination with fluorescence microscopy. In order to evaluate whether the nisin incorporation could modify the film surface properties, contact angle measurements and scanning e…

Comportamento reologico di nanocompositi a base di miscele HDPE/PA6

La preparazione di sistemi nanocompositi a base di miscele polimeriche suscita notevole interesse perché offre potenzialmente l’opportunità di combinare in maniera sinergica in un unico materiale diverse proprietà non possedute singolarmente da nessun polimero. In generale, le caratteristiche di questi sistemi polifasici dipendono certamente dalla natura dei costituenti, ma anche dalla morfologia finale del materiale: il controllo della dispersione e della dimensione delle particelle nonché dell’adesione interfacciale tra fasi (polimero/polimero, polimero/carica) costituiscono perciò parametri critici per il successo di questi materiali. Scopo di questo lavoro è stato valutare l’influenza d…

Reprocessing of PLA/graphene nanoplatelets nanocomposites

This work reports a study on the effect of multiple reprocessing on the properties of poly(lactic acid) (PLA) filled with graphene nanoplatelets (GnP) compared to the melt reprocessed neat polymeric matrix. In particular, morphological, X-Ray Diffraction and Micro-Raman analyses, intrinsic viscosity measurements, thermal, rheological and mechanical tests were carried out on materials reprocessed up five times by means of a single screw extruder. The results indicated that the presence of GnP decreased the degradation rate as a function of the reprocessing cycles in comparison with the neat PLA that, on the contrary, showed a more drastic reduction of the molecular weight. Moreover, the repr…

Photo-stability of LDPE/EVA – based nanocomposite films

Preparazione e caratterizzazione di fibre a base di PCL con proprietà antimicrobiche per applicazioni chirurgiche

Effetto dei metodi di lavorazione sulle proprietà di nanocompositi PLA/idrotalcite

PLA based biocomposites reinforced with Arundo donax fillers

Abstract In this work, for the first time, a natural and almost inexpensive filler obtained by grinding the culms of Arundo donax was used to prepare PLA based biocomposites. The composites were prepared by melt compounding PLA with A. donax filler (ADF). The influence of the content and size of ADF on the morphology and on the mechanical and thermal properties of PLA–ADF composites was evaluated. Moreover, ADF was extracted from composites to evaluate the effect of processing on morphology and dimensions of the incorporated filler. Furthermore, the experimental elastic moduli of the biocomposites have been fitted, employing two theoretical models, i.e., Hill and Halpin–Tsai. The results sh…

Combining carvacrol and nisin in biodegradable films for antibacterial packaging applications

Abstract In this work, the feasibility of antibacterial biopolymeric films containing carvacrol (CRV) and a nisin commercial formulation (Nis) for potential food packaging applications was investigated. As polymer matrix, a commercial biodegradable polymer formulation of Mater-Bi (MB) was chosen due to its significant food packaging applications. CRV and Nis were chosen due to their well-established antibacterial properties and their potential synergistic effect. MB/CRV, MB/Nis, and MB/CRV/Nis systems were produced by melt mixing and compression molding. The mechanical properties of the films were evaluated by tensile tests. Differential scanning calorimetry was assessed aiming at investiga…

Polyphasic Characterization of Microbiota of “Mastredda”, a Traditional Wooden Tool Used during the Production of PDO Provola dei Nebrodi Cheese

The biofilms of the wooden tables used for the acidification of the curd were investigated for PDO Provola dei Nebrodi cheese, a traditional stretched cheese made in eastern Sicily (southern Italy) from raw cows’ milk. To this purpose the wooden tables of four dairy facilities were analysed for their microbiota by scanning electron microscopy (SEM) analysis and a combined culture-independent and -dependent microbiological approach. SEM inspection showed an almost continuous biofilm formation. MiSeq Illumina analysis identified 8 phyla, 16 classes, 25 orders, 47 families and 50 genera. Corynebacterium, Bifidobacterium and lactic acid bacteria (LAB) were detected in all samples. In particular…

Use of Biochar as Filler for Biocomposite Blown Films: Structure-Processing-Properties Relationships

In this work, biocomposite blown films based on poly(butylene adipate-co-terephthalate) (PBAT) as biopolymeric matrix and biochar (BC) as filler were successfully fabricated. The materials were subjected to a film-blowing process after being compounded in a twin-screw extruder. The preliminary investigations conducted on melt-mixed PBAT/BC composites allowed PBAT/BC 5% and PBAT/BC 10% to be identified as the most appropriate formulations to be processed via film blowing. The blown films exhibited mechanical performances adequate for possible application as film for packaging, agricultural, and compost bags. The addition of BC led to an improvement of the elastic modulus, still maintaining h…

Competition between chain scission and branching formation in the processing of high-density polyethylene: effect of processing parameters and of stabilizers

Two samples of high-density polyethylene with different molecular weight were processed in a batch mixer and the rheological and structural properties were investigated. In particular, the effect of different processing parameters and the eventual presence of different stabilizers were evaluated. Actually, two reactions may occur during processing: branching/crosslinking or chain scission. The results indicate that when the processing conditions promote a scarce mobility of the macromolecular chains (lower temperatures, lower mixing speed, and higher molecular weight), branching is more favored than chain scission. On increasing the mobility of the chain (higher temperature, higher mixing s…

Morphology, Rheological and Mechanical Properties of Isotropic and Anisotropic PP/rPET/GnP Nanocomposite Samples

The effect of graphene nanoplatelets (GnPs) on the morphology, rheological, and mechanical properties of isotropic and anisotropic polypropylene (PP)/recycled polyethylene terephthalate (rPET)-based nanocomposite are reported. All the samples were prepared by melt mixing. PP/rPET and PP/rPET/GnP isotropic sheets were prepared by compression molding, whereas the anisotropic fibers were spun using a drawing module of a capillary viscometer. The results obtained showed that the viscosity of the blend is reduced by the presence of GnP due to the lubricating effect of the graphene platelets. However, the Cox–Merz rule is not respected. Compared to the PP/rPET blend, the GnP led to a slight incre…

Graphene oxide-silica nanohybrids as fillers for PA6 based nanocomposites

Graphene oxide (GO) was prepared by oxidation of graphite flakes by a mixture of H2SO4/H3PO4 and KMnO4 based on Marcano's method. Two different masterbatches containing GO (33.3%) and polyamide-6 (PA6) (66.7%) were prepared both via solvent casting in formic acid and by melt mixing in a mini-extruder (Haake). The two masterbatches were then used to prepare PA6-based nanocomposites with a content of 2% in GO. For comparison, a nanocomposite by direct mixing of PA6 and GO (2%) and PA6/graphite nanocomposites were prepared, too. The oxidation of graphite into GO was assessed by X-ray diffraction (XRD), Micro-Raman spectroscopy, scanning electron microscopy (SEM), X-ray photoelectron spectrosco…

EVA antimicrobial films prepared by melt processing

Integration of PCL and PLA in a monolithic porous scaffold for interface tissue engineering.

A novel bi-layered multiphasic scaffold (BLS) have been fabricated for the first time by combining melt mixing, compression molding and particulate leaching. One layer has been composed by polylactic acid (PLA) presenting pore size in the range of 90-110µm while the other layer has been made of polycaprolactone (PCL) with pores ranging from 5 to 40µm. The different chemo-physical properties of the two biopolymers combined with the tunable pore architecture permitted to realize monolithic functionally graded scaffolds engineered to be potentially used for interface tissues regenerations. BLS have been characterized from a morphological and a mechanical point of view. In particular, mechanica…

Physical and biological properties of electrospun poly( d , l ‐lactide)/nanoclay and poly( d , l ‐lactide)/nanosilica nanofibrous scaffold for bone tissue engineering

Electrospun scaffolds exhibiting high physical performances with the ability to support cell attachment and proliferation are attracting more and more scientific interest for tissue engineering applications. The inclusion of inorganic nanoparticles such as nanosilica and nanoclay into electrospun biopolymeric matrices can meet these challenging requirements. The silica and clay incorporation into polymeric nanofibers has been reported to enhance and improve the mechanical properties as well as the osteogenic properties of the scaffolds. In this work, for the first time, the physical and biological properties of polylactic acid (PLA) electrospun mats filled with different concentrations of n…

Film Blowing of Biodegradable Polymer Nanocomposites for Agricultural Applications

Films for agricultural applications, such as greenhouses films or mulching films are generally made of polyolefins such as linear low-density polyethylene (LLDPE) or low-density polyethylene. However, the use of biodegradable and/or compostable polymers is increasing, which enjoy the additional advantage that they can be left on the site since a fine life would be gradually assimilated to the underlying soil. Nevertheless, biodegradable polymeric films often do not have suitable mechanical performances. In this work, biodegradable polymer-based nanocomposite films are prepared by film blowing and compared with traditional LLDPE based nanocomposites. In particular, a biodegradable polymer bl…

Annealing time dependent rheological properties of polyethylene based nanocomposites

A rapid and eco-friendly route to synthesize graphene-doped silica nanohybrids

International audience; In the present study, the possibility to synthesize graphene oxide (GO)-based nanohybrids with pure and O2-doped silica nanoparticles by a rapid and easy hydrothermal process has been explored. The nanohybrids were prepared by varying the type of silica nanoparticles (average diameter 7 nm or 40 nm) and the silica/GO weight ratio. All the materials were fully characterized by spectroscopic and morphological techniques.The experimental results revealed that it is possible to tune the characteristics of the obtained nanohybrids, such as morphology and amount of ester/ether linkages upon varying the preparation parameters, together with the nanosilica's typology and the…

Tunable release of Chlorhexidine from Polycaprolactone-based filaments containing graphene nanoplatelets

Abstract Graphene nanoplatelets (GNP) as fillers and Chlorhexidine (CHX), as an antibacterial agent, were incorporated in a polycaprolactone (PCL) matrix and processed into filaments by melt spinning. The influence of both drawing and formulation on the processability, spinnability, mechanical properties and release behaviour of these materials were deeply investigated by performing rheological, morphological analysis, tensile tests, and by measuring the cumulative release of CHX in PBS at 37 °C. Furthermore, Korsmeyer–Peppas model was adopted to study the kinetics release mechanism. The results showed that adding GNP did not alter the processability and spinnability of the systems. Further…

Nanocarbons in electrospun polymeric nanomats for tissue engineering: A review

Electrospinning is a versatile process technology, exploited for the production of fibers with varying diameters, ranging from nano- to micro-scale, particularly useful for a wide range of applications. Among these, tissue engineering is particularly relevant to this technology since electrospun fibers offer topological structure features similar to the native extracellular matrix, thus providing an excellent environment for the growth of cells and tissues. Recently, nanocarbons have been emerging as promising fillers for biopolymeric nanofibrous scaffolds. In fact, they offer interesting physicochemical properties due to their small size, large surface area, high electrical conductivity an…

Sustained release of carvacrol and cinnamaldehyde from polymeric films to control the monospecies and dual-species biofilm development by E. coli and S. aureus

Influence of the matrix on photo-oxidative degradation of polyolefin based nanocomposite films

Polycaprolactone-based scaffold for oil-selective sorption and improvement of bacteria activity for bioremediation of polluted water

Abstract A novel floatable and biodegradable sponge for the selective absorption of oil from water and potentially useful as cell carrier for bioremediation treatments was prepared in polycaprolactone (PCL). The eco-friendly process for fabricating the PCL sponge does not involve either synthetic routes or organic solvents, thus minimizing environmental hazard. In particular, the 3D porous materials have been prepared by mixing in the melt the polymer matrix with two water-soluble porogen agents (NaCl and PEG) and thereafter leaching the obtained PCL/NaCl/PEG composites in water. The PCL sponges here proposed are capable to remove different types of oily pollutants (up to 500 wt%), and were…

Biochar Particles Obtained from Agricultural Carob Waste as a Suitable Filler for Sustainable Biocomposite Formulations

In the context of sustainable and circular economy, the recovery of biowaste for sustainable biocomposites formulation is a challenging issue. The aim of this work is to give a new life to agricultural carob waste after glucose extraction carried out by a local factory for carob candy production. A pyrolysis process was carried out on bio-waste to produce biofuel and, later, the solid residual fraction of pyrolysis process was used as interesting filler for biocomposites production. In this work, biochar particles (BC) as a pyrolysis product, after fuels recovery of organic biowaste, specifically, pyrolyzed carobs after glucose extraction, were added on poly(butylene-adipate-co-terephthalat…

Solid state 13C-NMR methodology for the cellulose composition studies of the shells of Prunus dulcis and their derived cellulosic materials.

Lignocellulosic fibers and microcellulose have been obtained by simple alkaline treatment from softwood al- mond shells. In particular, the Prunus dulcis Miller (D.A.) Webb. was considered as a agro industrial waste largely available in southern Italy. The materials before and after purification have been characterized by 13C CPMAS NMR spectroscopy methodology. A proper data analysis provided the relative composition of lignin and holo- cellulose at each purification step and the results were compared with thermogravimetric analysis and FT-IR. To value the possibility of using this material in a circular economy framework, the fibrous cellulosic material was used to manufacture a handmade c…

Nuove prospettive di impiego degli oli essenziali incorporati in materiali polimerici: sviluppo di "packaging" antimicrobici

Le nuove prospettive di impiego degli oli essenziali e dei loro componenti incorporati in sistemi polimerici aprono nuovi orizzonti nella progettazione di superfici e imballaggi alimentari attivi finalizzati al controllo della crescita microbica. Film rivestiti o impregnati con oli essenziali, in grado di interfacciarsi con l'ambiente circostante e di rilasciare le molecole attive, potrebbero contribuire ad un sostanziale miglioramento del prodotto in termini di sicurezza, shelf-life e conservazione.

Lemongrass Plant as Potential Sources of Reinforcement for Biocomposites: A Preliminary Experimental Comparison Between Leaf and Culm Fibers

AbstractNowadays, the world requires more sustainable and eco-friendly materials to replace or limit the usage of synthetic materials. Moreover, several researchers focused their attention on the use of agricultural sources as reinforcement for biocomposites since they are abundant, cost-effective and environmentally favorable sources. In such a context, purpose of the present paper is the evaluation of lemongrass plant (Cymbopogon flexuosus) as possible source of natural reinforcement for biocomposites. To this aim, natural fibers were obtained from the leaf and the stem of lemongrass and their main properties were compared for the first time. To this scope, mechanical and thermal characte…

Effetto della presenza di piccoli quantitativi di PLA nel riciclo di contenitori in PET

Degradation of polymer blends: A brief review

Abstract The usefulness of any material, including polymer blends, depends on its degradability and durability. The blend composition can significantly affect the degradative behavior of a polymer blend and can differ from the degradation routes of the pure components since the interactions among different species in the blends during degradation, and among the degradation products, can occur. These reactions can lead either to an acceleration of the degradation rate or to a stabilizing effect in comparison with the pure components. Thus, the additive rule cannot be often applied in case of degradation of polymer blends and, therefore, it is difficult to predict the degradative behavior of …

PLA graphene nanoplatelets nanocomposites: Physical properties and release kinetics of an antimicrobial agent

Abstract Graphene nanoplatelets (GnP) as filler and ciprofloxacin (CFX) as biocide were incorporated via melt-compounding into poly(lactic acid) (PLA) to obtain biopolymer-based nanocomposites with antimicrobial properties. GnP were added with the aim of improving the mechanical properties of the antimicrobial system and tuning the drug release. The obtained systems were mechanically characterized in tensile mode by quasi-static and dynamic mechanical tests. Furthermore, rheological measurements were performed. The morphology of the samples was analyzed through scanning electron microscopy (SEM). Moreover, a mathematical model, i.e. power law model, was used to fit the release data in order…

Prediction of the flow curves of thermoplastic polymer/clay systems from torque data

Abstract The aim of this work was to determine some relevant rheological parameters of polymer/clay systems using mixing torque and mixing speed data obtained during processing in an internal mixer. The method used was originally proposed by Marquez et al. for monophase polymers, and is here applied to polymer/clay systems for the first time. Several clay-containing composites based on different polymer matrices (i.e., LDPE, HDPE, PA6, EVA) were used to verify the effectiveness of the method for measuring the flow curves of these polymer/clay systems. The results indicated that, for all the systems at low clay level, the rheological curves calculated with the Marquez method fit quite well t…

Reactions Occurring during the Melt Mixing of Nylon 6 and Oxazoline−Cyclophosphazene Units

Specific reactions of amino and carboxyl end groups of Nylon 6 with the reactive oxazoline groups belonging to a cyclophosphazene compound (referred as CP20XA) were carried out at 240 °C for different times, under inert atmosphere. Ny6 polymers terminated with one specific reactive chain end (-COOH or NH2) were reacted with different amounts of CP20XA to study the kinetic order of the reactions. All Ny6-CP20XA reacted products soluble in trifluoroethanol (TFE) were well characterized by MALDI-TOF MS, FT-IR and ( 1H and 13C) NMR techniques. The MALDI-TOF results show that the oxazoline rings react with the carboxyl chain ends of Ny6 following second-order kinetics. The reactions with amino c…

Bionanocomposite Blown Films: Insights on the Rheological and Mechanical Behavior.

In this work, bionanocomposites based on two different types of biopolymers belonging to the MaterBi® family and containing two kinds of modified nanoclays were compounded in a twin-screw extruder and then subjected to a film blowing process, aiming at obtaining sustainable films potentially suitable for packaging applications. The preliminary characterization of the extruded bionanocomposites allowed establishing some correlations between the obtained morphology and the material rheological and mechanical behavior. More specifically, the morphological analysis showed that, regardless of the type of biopolymeric matrix, a homogeneous nanofiller dispersion was achieved

IMPROVED STABILITY OF GRAPHENE OXIDE-SILICA NANOHYBRIDS AND RELATED POLYMER-BASED NANOCOMPOSITES

Although its promising properties make the graphene oxide (GO) very interesting as filler for polymer matrices, some problems related to its thermal stability in the region which ranges from 80 to 200 °C, are crucial for the possibility to melt process GO together with practically all the polymers [1,2]. Moreover, above 100 °C GO lamellae were found to become stacked. In this work, two different ways to preserve the GO structure and ensure its dispersion within different polymer matrices have been investigated and schematized in Fig. 1. Exfoliation plays a key-role in the achievement of good mechanical properties since it preserves the GO from both stacking phenomena. The capability of sili…

Modifica superficiale di film di polietilene–co–acido acrilico

Photo-oxidation Behaviour of EVA Antimicrobial Films

Melt Processed PCL/PEG Scaffold with Discrete Pore Size Gradient for Selective Cellular Infiltration

In order to develop scaffold able to mimic the natural gradient properties of tissues, biphasic and triphasic approaches were adopted. In this work, polycaprolactone/polyethylene glycol (PCL/PEG) scaffolds were prepared by using a combination of melt mixing and selective leaching without harmful solvents. The method permitted to develop three-layer scaffolds with high control of porosity and pore size. The mechanical properties were evaluated under physiological condition in order to simulate the real conditions of work. Co-culture of osteoblastic and fibroblastic mice cells were carried out in order to study the differential cellular permeation through the different pore size layers.

Streptomyces coelicolor Vesicles: Many Molecules To Be Delivered

ABSTRACT Streptomyces coelicolor is a model organism for the study of Streptomyces, a genus of Gram-positive bacteria that undergoes a complex life cycle and produces a broad repertoire of bioactive metabolites and extracellular enzymes. This study investigated the production and characterization of membrane vesicles (MVs) in liquid cultures of S. coelicolor M145 from a structural and biochemical point of view; this was achieved by combining microscopic, physical and -omics analyses. Two main populations of MVs, with different sizes and cargos, were isolated and purified. S. coelicolor MV cargo was determined to be complex, containing different kinds of proteins and metabolites. In particul…

Structural and thermal stability of graphene oxide-silica nanoparticles nanocomposites

Abstract The investigation of the thermal stability up to 400 °C of Graphene Oxide (GO) and GO-silica nanoparticles (n-SiO2) composites prepared by direct mixture of GO and n-SiO2 is reported. Using Scanning Electron Microscopy, X-ray Photoelectron Spectroscopy, Energy Dispersive X-ray analysis, Atomic Force Microscopy, Raman and Infrared absorption measurements a thorough characterization of the prepared materials is carried out. By deepening the changes induced in the 2D Raman spectral region of GO at about 2900 cm−1 the comprehension of an interplay, driven by the thermally induced changes of the material, between inter-valley and intra-valley vibrational transitions is elucidated. This …

Polysaccharide nanocrystals as fillers for PLA based nanocomposites

The development of green nanocomposites based on biopolymers and bio-based nanofillers has attracted over the recent years the attention of academic and industrial research. Indeed, these nanocomposites could replace some oil-derived polymers and thus helping to overcome environmental problems. In this regard, PLA as matrix and polysaccharide nanocrystals as fillers are the most promising components to obtain high-performance green bio-nanocomposites suitable for different applications, particularly for packaging and biomedical applications. Indeed, at present, due to its processability, mechanical and biological properties, as well as its commercial availability, poly(lactic acid) (PLA) po…

Surface modification of poly(ethylene-co-acrylic acid) with amino-functionalized silica nanoparticles

In this work we studied the possibility to achieve a hybrid-surface through the modification, via a facile wet chemical process, of the surface of films of poly(ethylene-co-acrylic acid) (EAA) with amino-modified silica nanoparticles. Films of EAA were preliminarily activated by the introduction of -COCl groups on their surface. Silica nanoparticles were thereafter covalently bound on the polymeric surface as confirmed by FTIR, ATR-FTIR, XPS, NMR and SEM determinations. The nanoparticles formed a multilayer on the film surface and covered almost uniformly the whole film surface. Direct measurements of superficial amino groups by titration allowed us to detect a concentration of about 18 nmo…

In vitro Antifungal Activity of Biopolymeric Foam Activated with Carvacrol

Background: Active packaging represents a defining strategy to improve food quality and safety of the packaged foods. This study aimed to evaluate the in vitro ability of commercial biopolymeric foams, namely Mater-Bi (MB), activated with 20% of carvacrol, to develop a completely biodegradable and compostable packaging to inhibit the growth of spoilage and pathogenic yeasts.
 Methods: MB foams, with and without carvacrol, were produced by melt mixing and the foaming process was performed in a laboratory press. The antifungal activity of foams containing carvacrol was tested applying the disk diffusion method. Statistical analysis was done using XLStat software version 7.5.2 for Excel.&…

Scaffold con gradiente della dimensione dei pori per la migrazione selettiva di cellule eterotipiche

Modification of viscoelastic properties of polyethylene based nanocomposites after thermal treatment

Influence of Drawing on the Antimicrobial and Physical Properties of Chlorhexidine-Compounded Poly(caprolactone) Monofilaments

In this work, we prepared poly(caprolactone) (PCL) monofilaments incorporating different amounts of the antiseptic chlorhexidine diacetate (CHX) and evaluated the effect of “online” drawing during the melt spinning or of an “offline” cold drawing on the antimicrobial and physical properties of PCL/CHX monofilaments. The results showed that the drawing conditions strongly affected the properties of the threads. In particular, the filaments exhibited antimicrobial activity for all the draw ratios (DR) adopted, but on increasing DR the antibacterial efficiency reduced. These results were correlated with the CHX surface concentration and with the release kinetics.

Effetto della preparativa sulle proprietà di nanocompositi a base di ossido di grafene

Antibacterial biopolymeric foams: Structure–property relationship and carvacrol release kinetics

Abstract In this work, the feasibility of antibacterial biopolymeric foams containing carvacrol (CRV) for potential food packaging applications was investigated. Sodium bicarbonate (SB) was chosen as foaming agent and a commercial biodegradable polymer, Mater-Bi® (MB), as a matrix. MB/SB and MB/SB/CRV systems were prepared by melt mixing and the foaming process was conducted in a laboratory press. The influence of foaming agent and antibacterial additive content was investigated. The foamed samples were characterized through morphological analysis, mechanical tests and measurements of CRV release kinetics. Moreover, a mathematical model, i.e. power law model, was used to fit the release dat…

Modification of carboxyl groups of poly(ethylene-co-acrylic acid) via facile wet chemistry method: A kinetic study

Abstract In this work, we present the results of a kinetic study of the surface modification of the carboxyl group of poly(ethylene-co-acrylic acid) into acyl chloride. Reaction temperature and time, concentration of the reactants, kind of agitation have been changed in order to understand their effect on the conversion. A study on the penetration of the reaction inside the sample bulk was also performed. The results indicate that, when short reaction times are adopted, the reaction limits to the outer layers of the samples and, in this case, on increasing the temperature, the concentration of the reactants and the stirring allows having a faster kinetic. At longer reaction times, the react…

Rheological Behaviour of polyolefin based nanocomposites in isothermal and non-isothermal elongational flow

Influence of Nisin on Photo-stability of EVA Antimicrobial Films

On The Use Of Polyolefins Based Nanocomposites For Film Blowing Applications

Tryptophan promotes morphological and physiological differentiation in Streptomyces coelicolor.

The molecular mechanisms regulating tryptophan biosynthesis in actinomycetes are poorly understood; similarly, the possible roles of tryptophan in the differentiation program of microorganism life-cycle are still underexplored. To unveil the possible regulatory effect of this amino acid on gene expression, an integrated study based on quantitative teverse transcription-PCR (qRT-PCR) and proteomic approaches was performed on the actinomycete model Streptomyces coelicolor. Comparative analyses on the microorganism growth in a minimal medium with or without tryptophan supplementation showed that biosynthetic trp gene expression in S. coelicolor is not subjected to a negative regulation by the …

Multilayer porous PLA scaffolds for tissue engineering applications

Structure-properties relationships in melt reprocessed PLA/hydrotalcites nanocomposites

In this work the effect of multiple reprocessing was studied on molecular structure, morphology and properties of poly(lactic acid)/hydrotalcites (PLA/HT) nanocomposites compared to neat PLA. In addition, the influence of two different kinds of HT – organically modified (OM-HT) and unmodified (U-HT) – was evaluated. Thermo-mechanical degradation was induced by means of five subsequent extrusion cycles. The performance of the recycled materials was investigated by mechanical and rheological tests, differential scanning calorimetry (DSC), intrinsic viscosity measurements and SEM observation. The results indicated that the best morphology was achieved in the systems incorporating OM-HT. On inc…

Mechanical behavior of polylactic acid/polycaprolactone porous layered functional composites

Abstract Biopolymeric porous devices exhibiting graded properties can play a crucial role in several fields, such as tissue engineering or controlled drugs release. In this context, the gradient of a specific property can be achieved by developing porous laminates composed by different types of materials. This work presents for the first time a multi-phasic porous laminate based on polycaprolactone (PCL) and polylactic acid (PLA) prepared by combining melt mixing, compression molding and particle leaching. All the materials were characterized from a morphological and a mechanical point of view. The results put into evidence the possibility to tune and to predict the mechanical properties by…

Rapid and eco-friendly synthesis of graphene oxide-silica nanohybrids

Physical properties of virgin-recycled ABS blends: Effect of post-consumer content and of reprocessing cycles

Abstract Virgin/post-consumer ABS (pc-ABS) blends were re-processed and re-formed up to three times. The effect of pc-ABS content and of reprocessing cycles on the physical properties of the prepared blends was evaluated by mechanical tests (tensile, flexural and impact tests) and by rheological and thermo-mechanical measurements. The processability of pc-ABS blends was not substantially different by that of virgin ABS up to two recycling steps even if the third one induced a slightly decrease of viscosity, more remarkable on increasing the pc-ABS content. The mechanical and thermo-mechanical properties of the samples worsened on increasing the level of pc-ABS and after each reprocessing op…

Preparazione e caratterizzazione di film a base di EVA con proprietà antimicrobiche

Mechanism of formation of char coating in LDPE/organoclay nanocomposites

Influence of Drawing on the Antimicrobial and Physical Properties of Chlorhexidine-Compounded Poly(caprolactone) Monofilaments

In this work, we prepared poly(caprolactone) (PCL) monofilaments incorporating different amounts of the antiseptic chlorhexidine diacetate (CHX) and evaluated the effect of "online" drawing during the melt spinning or of an "offline" cold drawing on the antimicrobial and physical properties of PCL/CHX monofilaments. The results showed that the drawing conditions strongly affected the properties of the threads. In particular, the filaments exhibited antimicrobial activity for all the draw ratios (DR) adopted, but on increasing DR the antibacterial efficiency reduced. These results were correlated with the CHX surface concentration and with the release kinetics.

Preparation, characterization and hydrolytic degradation of PLA/PCL co-mingled nanofibrous mats prepared via dual-jet electrospinning

Abstract PLA/PCL co-mingled nanofibrous mats were prepared via multi-jet electrospinning. The concentration of PLA and PCL in the co-mingled mats were controlled by changing the flow rate of the two polymer solutions. The amount of PLA and PCL in the co-mingled nanofibrous mats was monitored by UV–Vis measurements through a colored dye added to PLA and by FTIR-ATR analysis. Morphology and mechanical properties of the nanofibrous mats were respectively examined by scanning electron microscopy (SEM) and tensile tests. Water contact angles measurements were also carried out in order to investigate the wettability of the materials. Finally, the hydrolytic degradation of the mats in buffer solut…

Arundo Donax particles as reinforcement for PLA based composites

Aim of this work was to use particles obtained by grinding the culms of Arundo Donax used as reinforcement for PLA based composites. The influence of the content (10 wt% and 20 wt%) and size (150-300 μm and 300-500 μm) of Arundo Donax filler (ADF) on the morphology and on the properties of PLA-ADF composites was evaluated. The composites were prepared by melt compounding the PLA with ADF using a co-rotating modular twin screw extruder. For comparison, neat PLA was processed under the same conditions. Both the neat PLA and the composites were characterized by SEM, DSC, tensile and flexural measurements.

Effetto di differenti metodi di preparazione sulle proprietà morfologiche e fisiche di nanocompositi a base di miscele HDPE/PA6

Melt development of biphasic functionally graded scaffold

Interface tissue engineering requires scaffolds that temporary replace the mechanical function of transition regions between two adjacent tissues. The presence of multi-phasic bio-structures that gradually change are typical features of interface tissues such as ligament-to-bone, tendon-to-bone and cartilage-to-bone. In this work, bi-layered scaffolds (BLS) composed by PLA with pores in the range of 90-110 µm and PCL with pores ranging from 5 to 40 µm were prepared by combining melt mixing, compression molding and particulate leaching. The principal advantages of this method lay in the absence of organic solvent during the preparation and in the easy control and high predictability of poros…

Effect of processing temperature and mixing time on the properties of PP/GnP nanocomposites

Abstract During processing of molten polymers the thermal and mechanical stress acting on the melt in presence of oxygen can induce degradation with a modification of the chemical structure of the polymers. This picture can become even more relevant if the melt is a multiphasic polymer system. In this last case, the effects of the degradation depend also on the presence of a second phase and on the interactions between the two phases. In this work, the effect of the processing conditions, temperature and time, have been considered in order to investigate the thermo-mechanical and thermo-oxidative degradation of nanocomposites made by polypropylene and different contents of graphene nanoplat…

Preparation and Characterization of PLA-Hydrotalcite Nanocomposites

Film di EVA con attività antibatterica

PBAT Based Composites Reinforced with Microcrystalline Cellulose Obtained from Softwood Almond Shells

This study explores the processability, mechanical, and thermal properties of biocompostable composites based on poly (butylene adipate-co-terephthalate) (PBAT) as polymer matrix and microcrystalline cellulose (MCC) derived from softwood almond (Prunus dulcis) shells (as-MCC) as filler at two different weight concentration, i.e., 10 wt% and 20 wt%. The materials were processed by melt mixing and a commercial MCC (c-MCC) was used as filler comparison. The fibrillar shape of as-MCC particles was found to change the rheological behavior of PBAT, particularly at the highest concentration. The melt mixing processing allowed obtaining a uniform dispersion of both kinds of fillers, slightly reduci…

Effect of a Compatibilizer on the Morphology and Properties of Polypropylene/Polyethylentherephthalate Spun Fibers

Fibers spun by melt spinning of binary and ternary polypropylene/ polyethylenetherephthalate blends have been produced and characterized in order to investigate the effect of a compatibilizer on their morphology and mechanical properties. The compatibilizer was a maleic anhydride-functionalized rubber copolymer. The effect of the compatibilizer was well evident in the isotropic state, as the morphology became very fine, the size of the dispersed particles was very small, and the adhesion was better. The effect of the compatibilizer on the mechanical properties is very relevant, especially in the elongation at break. On the contrary, no relevant effect was observed in the anisotropic oriente…

Preparazione e caratterizzazione di film poliolefinici nanocompositi per applicazioni in agricoltura

Preparation and characterization of polyolefin- based nanocomposite blown films for agricultural applications

Polyolefin-based films were prepared in the presence of two different organo-modified clays and characterized. The influence of organo-modifier and matrix composition on film morphology and properties were investigated using SEM, XRD, UV-Vis, FT-IR, contact-angle measurements and mechanical tests. The filler increased the films' rigidity and tear strength. Transparencies were almost unchanged in the visible range, but were reduced for harmful radiation. The presence of the clay increases the greenhouse effect, i.e. it hinders the passage of thermal emission from the soil to the outer part of the greenhouse during the night. The wettability of the materials was not influenced by the presence…

Preparation and mechanical characterization of polycaprolactone/graphene oxide biocomposite nanofibers

Biocomposite nanofiber scaffolds of polycaprolactone (PCL) filled with graphene oxide (GO) were prepared using electrospinning technology. Morphological and mechanical properties of the scaffolds were characterized in dry and wet environment. The results showed that the successful incorporation of GO nanosheets into PCL polymer nanofibers improved their mechanical properties. Furthermore it was demonstrated the higher performance achieved when GO is filled at low concentration in the nanofibers.

In-Depth Investigation of the Safety of Wooden Shelves Used for Traditional Cheese Ripening

ABSTRACT The main goal of this research was to characterize the bacterial diversity of the wooden boards used for aging traditional Sicilian cheeses and to evaluate whether pathogenic bacteria are associated with these surfaces. Eighteen cheese dairy factories producing three traditional cheese typologies (PDO Pecorino Siciliano, PDO Piacentinu Ennese, and Caciocavallo Palermitano) were selected within the region of Sicily. The wooden shelf surfaces were sampled by a destructive method to detach wood splinters as well as by a nondestructive brushing to collect microbial cells. Scanning electron microscopy showed the presence of almost continuous bacterial formations on the majority of the s…

TrpM, a Small Protein Modulating Tryptophan Biosynthesis and Morpho-Physiological Differentiation in Streptomyces coelicolor A3(2).

In the model actinomycete Streptomyces coelicolor A3(2), small open reading frames encoding proteins with unknown functions were identified in several amino acid biosynthetic gene operons, such as SCO2038 (trpX) in the tryptophan trpCXBA locus. In this study, the role of the corresponding protein in tryptophan biosynthesis was investigated by combining phenotypic and molecular analyses. The 2038KO mutant strain was characterized by delayed growth, smaller aerial hyphae and reduced production of spores and actinorhodin antibiotic, with respect to the WT strain. The capability of this mutant to grow on minimal medium was rescued by tryptophan and tryptophan precursor (serine and/or indole) su…

Photo-oxidation of polypropylene/graphene nanoplatelets composites

Abstract The photo-oxidation behaviour of polymer nanocomposites depends not only on the photo-oxidation behaviour of the matrix, but also on the chemical composition, on the physical properties of the nanoparticles and on the possible interactions between the two phases. In the case of nanocomposites with carbonaceous particles, the main effect is a photo-stabilization due to the absorption of the UV energy and the radical scavenging action. In this work we investigated the effect of the presence of graphene nanoplatelets on the photo-oxidation behaviour of the polypropylene. The presence of the graphene nanoplatelets improves the photo-resistance of the polypropylene and this effect incre…

Effect of ultraviolet and moisture action on biodegradable polymers and their blend

In this work, the suitability of polylactic acid (PLA), polybutylene adipate terephthalate (PBAT) and PBAT/PLA blend samples to outdoor applications were investigated in terms of mechanical, morphological and visual properties in presence of ultraviolet action and water, finding that PLA in particular can be actually considered for such applications.

Photo-oxidative degradation of poly(ethylene-co-vinyl acetate)/nisin antimicrobial films

The photo-oxidative behaviour of different antimicrobial blown films based on poly (ethylene-co-vinyl acetate) (EVA) was studied. In particular, two samples of EVA containing different level of vinyl acetate comonomer (namely 14% and 28%) were used as matrices while nisin at different concentrations was used as antimicrobial agent. The degradation was followed by analyzing the changes in the spectroscopic behaviour and of the elongation at break measured in tensile tests. Moreover, changes in the antimicrobial activity of the films were followed by measuring the inhibition halo in agar diffusion tests. The results indicate that nisin acts as an excellent UV stabilizer for both samples of EV…

Rheological behaviour, filmability and mechanical properties of biodegradable polymer films

The rheological properties in shear flow and non isothermal elongational flow of two biodegradable polymers, belonging to two different classes of materials, have been measured and compared with those of a film blowing grade high density polyethylene in order to assess the filmability of these polymers. The mechanical properties of isotropic and anisotropic samples have been also reported.

Development and characterization of essential oil component-based polymer films: a potential approach to reduce bacterial biofilm

The development of new polymeric materials aimed to control the bacterial biofilm appears to be an important practical approach. The goal of the present study was to prepare and characterize poly(ethylene-co-vinyl acetate) copolymer (EVA) films containing citronellol, eugenol, and linalool and evaluate their efficiency on growth and biofilm formation of Listeria monocytogenes, Staphylococcus aureus, Staphylococcus epidermidis, Escherichia coli, and Pseudomonas aeruginosa in monospecies and dual species. The results showed that the addition of oil components influenced the elastic modulus (15 % decrease), the tensile stress (30 % decrease), the elongation at break (10 % increase), and the co…

Incorporation of an antibiotic in poly(lactic acid) and polypropylene by melt processing

Purpose In this work an antibiotic, ciprofloxacin (CFX), was incorporated into 2 different polymeric matrices, poly(lactic acid) (PLA) and polypropylene (PP), to provide them with antimicrobial properties. The influence of CFX content on release kinetics and on antimicrobial and mechanical properties was evaluated. Methods CFX was incorporated into both the polymers by melt mixing. Results The effect of CFX incorporation was found to strongly depend on which polymer matrix was used. In particular, the antimicrobial tests revealed that PLA samples containing CFX produced no inhibition zone and only a slight antibacterial activity was observed when the highest concentration of CFX was added t…

Electrospun PCL/GO-g-PEG structures: Processing-morphology-properties relationships

Abstract Polycaprolactone (PCL) biocomposite nanofiber scaffolds with different concentrations of graphene oxide (GO) and GO surface grafted with poly(ethylene glycol) (GO-g-PEG) were prepared by electrospinning. Morphological, mechanical as well as wettability characterizations of electrospun nanofibers were carried out. Results showed that the average diameter of PLA/GO electrospun nanofibers decreased upon increasing the filler content. Differently, the diameter increased while using GO-g-PEG. Both nanofillers enhanced the electrospun PCL hydrophilicity even if PCL/GO-g-PEG samples exhibited improved wettability. The Young moduli of the composite nanofiber mats were improved by adding GO…

Effetto dello stiro sulle proprietà fisiche e antimicrobiche di fibre a base di PCL contenenti clorexidina

On the use of hydrotalcite in PLA based composites

Comparison of Different Processing Methods to Prepare Poly(lactid acid)–Hydrotalcite Composites

The effect of the compounding method on the morphology and on the properties of poly(lactic acid) (PLA)-hydrotalcite (HT) composites was studied. Moreover, the influence of two different kinds of HT - organically modified (OM-HT) and unmodified (U-HT) - and their concentration was evaluated. The composites were prepared using either a single screw extruder (SSE), a counter rotating twin-screw compounder (TSC) or a corotating twin-screw extruder (TSE). The prepared materials were characterized by scanning electron microscopy, gel permeation chromatography (GPC) analysis, mechanical and rheological measurements. The results indicated that the best morphology, i.e., particles dimension and dis…

Reactivity of cyclophosphazenes with end functionalised Ny6 samples and EAA copolyme

Processing and characterization of highly oriented fibres of biodegradable nanocomposites

Abstract Biodegradable polymeric materials are becoming day by day ever more important in packaging, agriculture, single-use cutleries and other large consumer applications. The major part of those materials is used under the form of film, i.e. subjected to elongational flow, but the main problem is that they often offer poor mechanical properties. Adding nanofillers, like Multi Walled Carbon Nanotubes (MWCNTs) may solve this problem but only if there is a full control of their orientation inside the material. Aim of this work is to investigate the processing-properties-morphology relationships for a system prepared under elongation flow of MaterBi and commercial MWCNTs. The materials were …

Investigation on the Properties and on the Photo-Oxidation Behaviour of Polypropylene/Fumed Silica Nanocomposites

This work investigates the effects of very small amounts of fumed silica on the morphology and on the rheological and mechanical behaviour of polypropylene nanocomposites and on their photo-oxidation behaviour. Polypropylene nanocomposites were prepared using a twin-screw corotating extruder with 0, 1 and 2 wt/wt% of SiO2. Morphological, mechanical, thermomechanical and rheological properties were examined. It was found that the viscosity of the matrix is reduced by the presence of the silica nanoparticles, suggesting a poor adhesion between the two phases and probably some lubricating effect. On the contrary, the mechanical and, in particular, the thermomechanical properties of the matrix …

Physical and antibacterial properties of PLA electrospun mats loaded with carvacrol and nisin

Functional, biopolymeric electrospun structures for the controlled release of antimicrobial agents are gaining in-creasing interest in food packaging applications. In this study, the physical and antibacterial performances of ternary systems composed of polylactic acid (PLA) electrospun mats loaded with 20 wt% of different relative amounts of carvacrol (CRV) and a commercial nisin formulation (Nis) were assessed. Scanning electron micrographs displayed micro-scaled fibers with different diameter size distributions depending on the relative concentrations of the additives. The PLA/CRV/Nis membranes??? wettability was affected by the relative amount of CRV and Nis loaded, switching from hydro…

Structure–Property Relationships in Bionanocomposites for Pipe Extrusion Applications

In this work, bionanocomposites based on different biodegradable polymers and two types of nanofillers, namely a nanosized calcium carbonate and an organomodified nanoclay, were produced through melt extrusion, with the aim to evaluate the possible applications of these materials as a potential alternative to traditional fossil fuel-derived polyolefins, for the production of irrigation pipes. The rheological behavior of the formulated systems was thoroughly evaluated by exploiting different flow regimes, and the obtained results indicated a remarkable effect of the introduced nanofillers on the low-frequency rheological response, especially in nanoclay-based bionanocomposites. Conversely, t…

Conductive polymer composites based on cyclic butylene terephtalate oligimers and carbon fibers

Thermo-oxidative ageing of an organo-modified clay and effects on the properties of PA6 based nanocomposites

a b s t r a c t In this work a careful investigation on the degradation of an organically modified montmorillonite sample (Cloisite 15A) thermal treated under different atmospheres, namely nitrogen, air and oxygen enriched atmosphere was performed. The exposure time of the thermal treatment ranged between 5 and 300 min. The chemical composition evolution as function of the thermal treatment conditions of the clay organic modifier was monitored by means of combined thermogravimetry/Fourier transform infrared spectroscopy (TGA-FTIR). Moreover, the morphological behaviour of treated Cloisite 15A sam- ples as function of the time and of the decomposition atmosphere was investigated by X-ray dif…

Effetto della temperatura sull’attività antimicrobica e antibiofilm di aldeide cinnamica e carvacrolo incorporati in film polimerici

Recycling of a Biodegradable Polymer Blend

Mechanical recycling is one of the possible ways to enhance the value of postconsumer plastic materials. However, the final performance of the recycled material will strongly depend on the quality of the selection made on the recycled product and on the degradation of the properties. In this context, the present study examines the effect of reprocessing for five successive extrusion cycles on the rheological, mechanical and thermal properties of a poly(butylene adipate-co-terephthalate) (PBAT)-based blend on samples reprocessed in both dry and wet conditions. The results showed that when the sample was processed after drying, degradation of the material was less than when it was processed i…

The role of organoclay and matrix type in photo-oxidation of polyolefin/clay nanocomposite films

Abstract In this paper the photo-oxidation behaviour of polyolefin/clay nanocomposite films was studied; in particular, the effect of the amount of organo-modifier and the matrix polarity on the photo-oxidation was investigated. Two different organo-modified clays and compositions of LDPE/EVA blend films were used and the photo-oxidation was followed by mechanical and spectroscopic analyses. The organoclay and matrix type strongly influence the photo-oxidative behaviour of nanocomposite films. The films filled with CL15A show a faster loss of mechanical performance and higher carbonyl formation with respect to the films filled with the CL20A. Additionally, the LDPE based nanocomposite under…

Injection Molding and Mechanical Properties of Bio-Based Polymer Nanocomposites

The use of biodegradable/bio-based polymers is of great importance in addressing several issues related to environmental protection, public health, and new, stricter legislation. Yet some applications require improved properties (such as barrier or mechanical properties), suggesting the use of nanosized fillers in order to obtain bio-based polymer nanocomposites. In this work, bionanocomposites based on two different biodegradable polymers (coming from the Bioflex and MaterBi families) and two different nanosized fillers (organo-modified clay and hydrophobic-coated precipitated calcium carbonate) were prepared and compared with traditional nanocomposites with high-density polyethylene (HDPE…

Characterization and Processability of Blends of Polylactide Acid with a New Biodegradable Medium-Chain-Length Polyhydroxyalkanoate

In this work the processability and the mechanical performance of polylactide acid (PLA) based blends with a sample of a new biodegradable medium-chain-length poly (hydroxyalkanoate) (PHA) were investigated. The two polymers are incompatible with scarce adhesion and with the dispersed PHA particles size increasing with the PHA content. Rheological tests in shear flow indicate that adding PHA improves the processability of the matrix by increasing the content of this second component in the blend, as observed also for the torque curves, due to the very low viscosity of this new sample of PHA. The processability is only slightly worsened in non-isothermal elongational flow as the melt strengt…

Effect of kind and content of organo-modified clay on properties of PET nanocomposites

In this work we report the properties of nanocomposite based on PET with two different samples of organically modified montmorillonites. In particular, we studied the effect of the filler concentration on morphology, rheology, and mechanical performance, focusing our attention on the effect of the degradation phenomena of the clay modifiers. The results indicate that at low clay level the morphology achieved is mainly intercalated. On increasing the filler level, coalescence and/or bad defragmentation phenomena induce a coarser morphology, as confirmed by XRD, SEM, and TEM observations. When a more polar organic modifier is used to modify the clay, the particle adhesion and distribution is …

Effect of thermal cycles on the rheological behaviour of polymerclay nanocomposites

Presenza di PLA nel riciclo di PET

Toward the Decarbonization of Plastic: Monopolymer Blend of Virgin and Recycled Bio-Based, Biodegradable Polymer.

Decarbonization of plastics is based on two main pillars: bio-based polymers and recycling. Mechanical recycling of biodegradable polymers could improve the social, economic and environmental impact of the use of these materials. In this regard, the aim of this study was to investigate whether concentrations of the same recycled biopolymer could significantly affect the rheological and mechanical properties of biodegradable monopolymer blends. Monopolymer blends are blends made of the same polymers, virgin and recycled. A sample of commercially available biodegradable blend was reprocessed in a single-screw extruder until two extrusion cycles were completed. These samples were exposed to gr…

Effect of thermal treatment time on the rheological behaviour of PE based nanocomposites

“Compatibilization” through Elongational Flow Processing of LDPE/PA6 Blends

Polyamide/polyolefin blends have gained attention from the academia and the industry for several years. However, in order to optimize their properties, some drawbacks such as chemical incompatibility must be adequately overcome. This can be done by adding suitable compatibilizers. On the other hand, it is less known that suitable processing techniques may also lead to significant results. In a previous work on a low-density polyethylene/polyamide 6 (LDPE/PA6) blend, we found that the orientation due to elongational flow processing conditions could lead to an unexpected brittle&ndash

Effect of PCL/PEG-Based Membranes on Actinorhodin Production in Streptomyces coelicolor Cultivations

The actinomycetes, Gram-positive filamentous bacteria, are the most prolific source of natural occurring antibiotics. At an industrial level, antibiotics from actinomycete strains are produced by means of submerged fermentations, where one of the major factors negatively affecting bioproductivity is the pellet-shaped biomass growth. The immobilization of microorganisms on properly chosen supports prevents cell-cell aggregation resulting in improving the biosynthetic capability. Thus, novel porous biopolymer-based devices are developed by combining melt mixing and particulate leaching. In particular, polycaprolactone (PCL), polyethylene glycol (PEG), and sodium chloride (NaCl) with different…

Effect of biobased plasticizers, used as dispersing aids, on mechanical, rheological and thermal properties of micro fibrillated cellulose (MFC)/poly (lactic acid) (PLA) biocomposites over the time: how MFC controls the plasticizer migration?

Micro Fibrillated Cellulose (MFC) has gained interest both in academia and industry, but some critical issues must be overcome to exploit the industrial MFC/biocomposites uses. In particular, the first drawback is related to the MFC agglomeration during the primary processing. Encouraging results have been obtained using plasticizers, as dispersing aids, during the extrusion that optimizes the process parameters based on the variation of the melt viscosity. However, even if the plasticizer addition counterbalances the excessive biocomposite stiffness, caused by the addition of the MFC, its eventual migration from the finished product needs to be evaluated to avoid toughness reductions as we…

Preparation and characterization of 3D PLA porous scaffolds

Effect of small amounts of poly(lactic acid) on the recycling of poly(ethylene terephthalate) bottles

Abstract Poly(ethylene terephthalate) (PET) is one of the most used commodity polymers, especially for food and beverage applications, and its recycling is of great importance because of the possible use in the textile and construction industries. On the other hand, the interest in biodegradable polymers has led, in recent years, to the use of materials such as poly(lactic acid) (PLA) also in the food and beverage industry. The presence of small amounts of PLA in the PET waste can significantly affect the post-consumer recycling process. In this work, the effect of the presence of small amounts of PLA on the recycling of PET bottles is investigated by rheological, mechanical, morphological …

Nanohybrid surface based on covalent linkage of amino-functionalized silica nanoparticles on EAA polymeric substrate

Synthesis and self-assembly of a PEGylated-graphene aerogel

Abstract In the frame of this work, we present, for the first time, the synthesis and self-assembly of an aerogel built by graphene oxide-polyethylene glycol. The synthetic route involves at first the coupling of GO with an amino-terminated polyethylene glycol sample by carbodiimide in aqueous environment, and the subsequent conversion of the hydrogel achieved into an aerogel via freeze-drying. The 3D PEGylated graphene-based aerogel, characterized by spectroscopic, morphological, structural and mechanical analyses, displays an ultralight and highly porous (99.7%) network and possesses high mechanical properties together with a good biocompatibility.

Photo-oxidation of polyolefin/clay nanocomposite films: role of organoclay and matrix type

Rheological and mechanical properties of biodegradable nanocomposites

Polymer nanocomposites have gained huge interest over the last decade. However, traditional thermoplastic nanocomposites do not match the rising concern about environmental issues. Therefore, during the last years, the search for biodegradable polymer nanocomposites is gaining importance. Most of biobased (i.e. based on biodegradable/bioderived polymer matrices) nanocomposites have poly(lactic acid), PLA, as matrix. However, it is of clear interest to take into account also different biobased polymer matrices, such as MaterBi. In this work, we prepared bionanocomposites containing MaterBi or a PLA-based polymer matrix, with two different kinds of nanofillers (organomodified clay and nanosiz…

Antimicrobial activity of EVA blown films containing nisin

Imballaggi antimicrobici estrusi

Green Nanocomposites-Based on PLA and Natural Organic Fillers

Over the past decades, many efforts have been carried out for the development of novel green nanocomposites based on biopolymers and natural organic nanofillers. Indeed, these nanocomposites could replace some oil-derived polymers and thus helping to overcome environmental problems. In this regard, poly (lactic acid) (PLA) as matrix and polysaccharide nanocrystals (cellulose, chitin, and starch) as bio-based nanoreinforcements are the most promising components to obtain high-performance green nanocomposites. This chapter covers the basic features of PLA and polysaccharide nanocrystals derived from biomass-based raw materials such as cellulose, chitin, and starch. In particular, this chapter…

Fracture behavior and mechanical, thermal, and rheological properties of biodegradable films extruded by flat die and calender

The development of biodegradable materials for tailored applications, particularly in the field of polymeric films and sheets, is a challenging technological goal as well as a contribution to help protect the environment. Poly(lactic) acid (PLA) is a promising substitute for several oil-based polymers; however, to overcome its thermal and mechanical drawbacks, researchers have developed solutions such as blending PLA with polybutylene adipate terephthalate (PBAT), which is capable of increasing the ductility of the final material. In this study, PLA/PBAT binary blends, with minimum possible content of nonrenewable materials, were examined from processing, thermal, morphological, and rheolog…

Plasma modified PLA electrospun membranes for actinorhodin production intensification in Streptomyces coelicolor immobilized-cell cultivations

Most of industrially relevant bioproducts are produced by submerged cultivations of actinomycetes. The immobilization of these Gram-positive filamentous bacteria on suitable porous supports may prevent mycelial cell-cell aggregation and pellet formation which usually negatively affect actinomycete submerged cultivations, thus, resulting in an improved biosynthetic capability. In this work, electrospun polylactic acid (PLA) membranes, subjected or not to O2-plasma treatment (PLA-plasma), were used as support for immobilized-cell submerged cultivations of Streptomyces coelicolor M145. This strain produces different bioactive compounds, including the blue-pigmented actinorhodin (ACT) and red-p…

Processing – morphology – property relationships of polyamide 6/polyethylene blend–clay nanocomposites

In this work, we studied the effect of the method of preparation and of reprocessing on the morphology and, con- sequently, on the physical properties of polyamide 6 (PA6)/ high density polyethylene (HDPE)-clay nanocomposite blends in the presence of different compatibilizers. In particular, the nanocomposites were obtained by melt mixing using a co- rotating twin screw extruder (E1). The blends thus obtained were re-extruded (E2) under the same operating conditions. Moreover, blends with the same final composition were produced using a masterbatch of the compatibilizer with the clay prepared in a separated stage in a batch mixer (MB). All the materials were characterized by scanning electr…

Biocomposite PBAT/lignin blown films with enhanced photo-stability.

Lignin can be obtained as a byproduct during cellulose-rich pulp fibers production and it is habitually treated as waste or intended for low-value destinations. However, due to UV absorption and mechanical properties, lignin can contribute to the fabrication of biodegradable blown films with superior performances. In this study, it was established the suitability of lignin for manufacturing biocomposite PBAT blown films with higher stiffness and photo-oxidation resistance. The effect of the filler concentration on the melt rheological behavior in non-isothermal elongational flow was investigated. The results allowed us to choose the correct filler concentration for producing films through a…

CORRELATION BETWEEN THE CHEMICAL-PHYSICAL PROPERTIES OF CNT AND MACROSCOPIC PROPERTIES OF RELATED NANOCOMPOSITES: A STATISTICAL APPROACH

In the frame of this work, two different samples of CNTs, namely CNT 1 and CNT 2, were synthesized [1] with different degree of purity and aspect ratio and used as fillers either without any treatment or after a plasma-oxidation, to prepare polycarbonate (PC)-based nanocomposites by melt mixing. The influence of plasma treatment, filler content and type of CNTs on the mechanical, dynamic-mechanical, and electrical properties of the materials was assessed by a two level full factorial design. The morphological analysis carried out by SEM and TEM evidenced the formation of a nanohybrid structure when oxidized CNTs were used as filler. Generally speaking, CNT 2 showed the best dispersion and t…

Durability of biodegradable polymers for the conservation of cultural heritage

The use of polymers for conservation of cultural heritage is related to the possibility to slow down or stop natural deterioration which, in many cases, corresponds to stopping the entrance of liquid water and to favour spontaneous water vapour removal. Unfortunately, hydrophobicity is generally favoured by surface roughness and thus competitive with transparency. It is therefore important to find an optimal balance hydrophobicity, transparency and durability (especially to photooxidation). However, polymers typically used for applications in this field come from non-renewable resources and are not biodegradable. In this work, the mechanical, structural and optical properties of PLA, PBAT a…

PLA based biocomposites reinforced with Posidonia oceanica leaves

Abstract Biocomposites can valorize some natural products related to natural processes or crop and waste industries. In this work, leaves of Posidonia oceanica (PO), dominant sea grass in the Mediterranean Sea, were used to prepare PLA based biocomposites. Materials were prepared by melt mixing PLA with PO as filler. The morphology as well as the mechanical and thermal properties of PLA/PO composites were evaluated and related with the influence of the content and size of PO. Moreover, the experimental elastic moduli of the biocomposites was modelled employing the Halpin–Tsai (HT) model. Furthermore, in order to take into consideration the high porosity of PO leaves, the HT parameters relat…

Antimicrobial thermoplastic materials for biomedical applications prepared by melt processing

In this work thermoplastic polymers with antimicrobial properties were prepared by incorporating an antibiotic, i.e., ciprofloxacin (CFX), by melt processing. Two different polymers were used as matrices, i.e., polypropylene (PP) and poly(lactid acid) (PLA) and different concentrations of CFX have been incorporated. The antimicrobial properties, the release kinetic and the mechanical performances of the prepared materials were evaluated.

Preparation and characterization of multilayer porous PLA scaffolds

Carvacrol activated biopolymeric foam: An effective packaging system to control the development of spoilage and pathogenic bacteria on sliced pumpkin and melon

Abstract A commercial biodegradable starch-based polymer (Mater-Bi) was activated with carvacrol to develop a biodegradable and compostable polymer to be used in food packaging. Based on previous tests, carvacrol was added at 20 % weight of foam. MB foams, with and without carvacrol, were tested for their morphological characteristics, mechanical tests and kinetics of carvacrol release under refrigerated storage conditions. Carvacrol slightly increased the porosity of the foams, induced a reduction of the compressive elastic modulus (Ecom) of foamed MB from 6 to ∼ 3.4 MPa and a decrease of the tensile elastic modulus from ∼70 MPa to ∼16.5 MPa. Carvacrol release from the foam at 4 °C was alm…

Electroplated bismuth absorbers for planar NTD-Ge sensor arrays applied to hard x-ray detection in astrophysics

Single sensors or small arrays of manually assembled neutron transmutation doped germanium (NTD-Ge) based microcalorimeters have been widely used as high energy-resolution detectors from infrared to hard X-rays. Several planar technological processes were developed in the last years aimed at the fabrication of NTD-Ge arrays, specifically designed to produce soft X-ray detectors. One of these processes consists in the fabrication of the absorbers. In order to absorb efficiently hard X-ray photons, the absorber has to be properly designed and a suitable material has to be employed. Bismuth offers interesting properties in terms of absorbing capability, of low heat capacity (needed to obtain h…

Preparation and Characterization of Polyolefin-Based Nanocomposite Blown Films for Agricultural Applications

These kinds of filmshave,asaprimaryaim,tocreateafavorablemicro-climateto accelerate the plant growth.Thematerialsfortheseapplicationsmustpossessseveralspecificandpeculiarcharacteristics,suchastheabilitytobeshaped into films (even with wide dimensions and largethickness ranges), good deformability and tear resistancetogetherwithasufficientrigidity,transparencyforUVandIR radiation in particular regions of the spectrum, a goodresistance to photo-oxidative phenomena and for someapplications to provide a barrier for certain gases.Moreover, an important property requested for thematerials used for greenhouse covering is the capabilityto diffuse the light. In fact, according to some studies,diffused l…

Chemical Reactions occurring in the molten state between Ny6 and Oxazoline groups linked to a Cyclophosphazene moiety

Biopolymer based nanocomposites reinforced with graphene nanoplatelets

In this work, biopolymer based nanocomposites filled with graphene nanoplatelets (GnP) were prepared by melt compounding in a batch mixer. The polymer used as matrix was a commercial biodegradable polymer-blend of PLA and a copolyester (BioFlex®). The prepared materials were characterized by scanning electron microscopy (SEM), rheological and mechanical measurements. Moreover, the effect of the GnP amount on the investigated properties was evaluated. The results indicated that the incorporation of GnP increased the stiffness of the biopolymeric matrix.

Nuovi fili da sutura multifunzionali a rilascio controllato di sostanze antimicrobiche, antibiotiche, cicatrizzanti.

Oggetto di questa invenzione è un metodo e la relativa tecnologia di produzione per la preparazione di fili da sutura multifunzionali che possiedono proprietà antibiotiche e/o cicatrizzanti e/o antimicrobiche modulabili in funzione delle condizioni di preparazione. I fili possono avere tali proprietà singolarmente o contemporaneamente. In particolare è stata messa a punto una tecnologia che prevede l’incorporazione da fuso di un agente antibiotico e/o cicatrizzante e/o antimicrobico durante la preparazione dei fili da sutura. Il processo di filatura è in linea e tramite una modulazione della quantità di sostanza, delle condizioni di stiro (isotermo e non isotermo), è possibile regolare il d…

Combining in the melt physical and biological properties of poly(caprolactone) and chlorhexidine to obtain antimicrobial surgical monofilaments.

Bacterial infections on a sutured wound represent a critical problem, and the preparation of suture threads possessing antimicrobial properties is valuable. In this work, poly(caprolactone) (PCL) monofilaments were compounded at the concentration of 1, 2 and 4 % (w/w), respectively, to the antiseptic chlorhexidine diacetate (CHX). The incorporation was carried out in the melt by a single-step methodology, i.e. “online” approach. Mechanical tests revealed that the incorporation of CHX does not significantly change tensile properties of PCL fibres as the thermal profile adopted to prepare the compounded fibres does not compromise the antibacterial activity of CHX. In fact, CHX confers to comp…

A facile and eco-friendly route to fabricate poly(Lactic acid) scaffolds with graded pore size

Over the recent years, functionally graded scaffolds (FGS) gaineda crucial role for manufacturing of devices for tissue engineering. The importance of this new field of biomaterials research is due to the necessity to develop implants capable of mimicking the complex functionality of the various tissues, including a continuous change from one structure or composition to another. In this latter context, one topic of main interest concerns the design of appropriate scaffolds for bone-cartilage interface tissue. In this study, three-layered scaffolds with graded pore size were achieved by melt mixing poly(lactic acid) (PLA), sodium chloride (NaCl) and polyethylene glycol (PEG). Pore size distr…

Biocompositi a base di PLA rinforzati con cariche lignocellulosiche ricavate dalla canna comune

The Streptomyces coelicolor Small ORF trpM Stimulates Growth and Morphological Development and Exerts Opposite Effects on Actinorhodin and Calcium-Dependent Antibiotic Production

In actinomycetes, antibiotic production is often associated with a morpho-physiological differentiation program that is regulated by complex molecular and metabolic networks. Many aspects of these regulatory circuits have been already elucidated and many others still deserve further investigations. In this regard, the possible role of many small open reading frames (smORFs) in actinomycete morpho-physiological differentiation is still elusive. In Streptomyces coelicolor, inactivation of the smORF trpM (SCO2038) – whose product modulates L-tryptophan biosynthesis – impairs production of antibiotics and morphological differentiation. Indeed, it was demonstrated that TrpM is able to interact w…

Effect of adding new phosphazene compounds in polybutyleneterephthalate/polyamide blends. II: Effect of difefrent polyamides on the properties of extruded samples

Effect of different matrices and nanofillers on the rheological behavior of polymer-clay nanocomposites

In this work, a comprehensive study of the rheological behavior under shear and isothermal and nonisothermal elongational flow of low density polyethylene (LDPE) and ethylene-vinyl acetate copolymer (EVA) based nanocomposites was reported to evaluate their "filmability", that is, the ability of these material to be processed for film forming applications. The influence of two different kinds of organoclay - namely Cloisite 15A and Cloisite 30B - and their concentration was evaluated. The presence of filler clearly affects the rheological behavior in oscillatory state of polyolefin-based nanocomposites but the increase of complex viscosity and the shear thinning are not dramatic. A larger st…

Effect of cold drawing on the antimicrobial and physical properties of PCL/CHX monofilaments

Nanofilled Thermoplastic–Thermoplastic Polymer Blends

Nanofillers can play two important roles in polymer blends. The first is the improvement of various properties such as mechanical, barrier, thermal, flame retardancy, and electrical properties. The second is the modification of miscibility/compatibility and morphology of polymer blends. The mechanism of action of nanoparticles to modify the morphology, interfacial properties, and performance of immiscible polymer blends relies on their localization, their interactions with polymer components, and the way these additives disperse within the polymer blend. The objective of this chapter is to review the research on nanofilled thermoplastic/thermoplastic polymer blends, paying particular attent…

Slow Pyrolysis as a Method for Biochar Production from Carob Waste: Process Investigation and Products’ Characterization

The zero-waste city challenge of the modern society is inevitably addressed to the development of model’s waste-to-energy. In this work, carob waste, largely used in the agro-industrial sector for sugar extraction or locust beangum (LBG) production, is considered as feedstock for the slow pyrolysis process. According to the Food and Agriculture Organization of the United Nations (FAO), in 2012, the world production of carobs was ca. 160,000 tons, mainly concentrated in the Mediterranean area (Spain, Italy, Morocco, Portugal, and Greece). To evaluate the biomass composition, at first, the carob waste was subjected to thermo-gravimetric analysis. The high content of fixed carbon suggest…

Oli essenziali: progressi scientifico-tecnologici per il controllo della crescita microbica

La contaminazione microbica degli alimenti e l'elevata diffusione di ceppi antibiotico resistenti abili a produrre biofilm rappresentano un serio problema di carattere igienico-sanitario. La ricerca è oggi finalizzata allo sviluppo di alternative antimicrobiche, sicure ed efficaci. Tra i composti più promettenti vi sono i prodotti naturali come gli oli essenziali ed i loro componenti. Un’ampia letteratura ne descrive l’efficacia nei confronti di batteri, virus, lieviti e muffe e ne suggerisce un possibile ruolo nella conservazione degli alimenti. In tale contesto, il progresso scientifico-tecnologico del settore ha consentito lo sviluppo di nuove soluzioni finalizzate alla progettazione di …

Potenziamento dell’attività antimicrobica di aldeide cinnamica e carvacrolo incorporati in film a base di etilen- vinil- acetato

PHOTO-OXIDATION OF PA6/GRAPHENE OXIDE FILMS

Graphene oxide (GrO) was synthesized with Marcano’s method [1] and added at 0.5 and 1 wt% loading content to a polyamide 6 (PA6). In particular, three different techniques have been used for the preparation of the nanocomposites: (i) melt blending in a batch mixer, (ii) solvent casting in formic acid, (iii) preparation of a masterbatch by solvent casting and further melt processing. The films (80 m) were photo-oxidized in a QU-V chamber up to about 100 hours. The effect of filler content and preparation technique on the photo-stability of the nanocomposites has been followed by monitoring the change of the mechanical and spectroscopic properties undergone upon artificial exposure to UV-B l…

Processing-property relationships of polypropylene/ciprofloxacin fibers

In this work we prepared polypropylene (PP) fibers incorporating an antibiotic, i.e. ciprofloxacin (CFX), by melt spinning. In particular, PP has been compounded with CFX at different concentrations by using a counter-rotating twin screw compounder. The PP/CFX fibers have been spun by using a capillary rheometer operating under a constant extrusion speed. The effect of “online” hot drawing during the melt spinning or of an “offline” cold drawing on the properties of PP/CFX fibers were evaluated. In particular, the influence of the drawing conditions on the mechanical properties and the release kinetics were studied. Moreover, the rheological behavior in non-isothermal elongation flow has be…

Development of polymeric functionally graded scaffolds: a brief review.

Over recent years, there has been a growing interest in multilayer scaffolds fabrication approaches. In fact, functionally graded scaffolds (FGSs) provide biological and mechanical functions potentially similar to those of native tissues. Based on the final application of the scaffold, there are different properties (physical, mechanical, biochemical, etc.) which need to gradually change in space. Therefore, a number of different technologies have been investigated, and often combined, to customize each region of the scaffolds as much as possible, aiming at achieving the best regenerative performance. In general, FGSs can be categorized as bilayered or multilayered, depending on the number…

Biopolymeric bilayer films produced by co-extrusion film blowing

Abstract Biodegradable packaging promises a more environmentally friendly future. Nevertheless, a single biopolymer often lacks of some important properties. In order to contribute to this challenge, biodegradable bilayer films from poly(lactic acid) (PLA) and MaterBi® were prepared in this work and compared with monolayer films obtained with both the polymers. The prepared films were fully characterized through morphological, mechanical, thermal, chemical, optical and water contact angle analyses. Furthermore, the hydrolytic degradation of monolayer and bilayer films was studied by performing tests at three different pH. The morphological analysis revealed that PLA/MaterBi bilayer films sh…

Orientation and exfoliation of clay nanoparticles in the spinning of a nanobiocomposite sample

Polymer nanobiocomposites represent a new group of materials filled with inert nanosized particles that show very interesting properties with respect to the matrix and the same biodegradability of the matrix. In this work we have studied the effect of the elongational flow on the morphology and dynamic-mechanical properties of a new nanobiocomposite made by a matrix of biodegradable PLA and a filler of organomodified montmorillonite.

Influence of PLA on the recycling of PET bottles

Preparation and characterization of PCL/GO-g-PEG biocomposite nanofiber scaffolds

Biocomposite nanofiber scaffolds of polycaprolactone (PCL) with different graphene oxide surface grafted with poly(ethylene glycol) (GO-g-PEG) concentrations were prepared by electrospinning. Morphological, mechanical as well as wettability characterization were carried out. Results showed that the average diameter of PLA/GO-g-PEG electrospun nanofibers increased by increasing the filler content. GO-g-PEG enhanced the electrospun PCL hydrophilicity as well as the Young modulus, in particular at low GO-g-PEG concentrations.

Effect of Different Matrices and Nanofillers on the Rheological Behavior of Polymer-Clay Nanocomposites

In this work, a comprehensive study of the rheologi-cal behavior under shear and isothermal and nonisothermal elongational flow of low density polyethylene (LDPE) and ethylene-vinyl acetate copolymer (EVA) based nanocomposites was reported to evaluate their "filmability", that is, the ability of these material to be processed for film forming applications. The influence of two different kinds of organoclay - namely Cloisite 15A and Cloisite 30B - and their concentration was evaluated. The presence of filler clearly affects the rheological behavior in oscil-latory state of polyolefin-based nanocomposites but the increase of complex viscosity and the shear thinning are not dramatic. A larger …

PLA-hydrotalcite nanocomposites: effect of processing methods

Effect of adding new phosphazene compounds to poly(butylene terephthalate)/polyamide blends. I: Preliminary study in a batch mixer

Abstract Poly(butylene terephthalate) (PBT) and a sample of polyamide have been melt processed in the presence of two new phosphazene compounds, namely 2,2-dichloro-4,4,6,6-bis[spiro(2′,2″dioxy-1′,1″biphenyl)]cyclotriphosphazene (2Cl-CP) and 2,2-bis-(2-methoxy-4-methyleneoxy-phenoxy)-4,4,6,6,-bis[spiro(2′,2″dioxy-1′,1″biphenyl)]cyclophosphazene (CP-2EPOX). The blends were prepared by using polyamide 6 (PA6) at 25/75 w/w and 75/25 w/w composition. In order to perform a preliminary analysis on the behaviour of the blends, the materials were prepared in a batch mixer. The materials have been completely characterized from a rheological, morphological, mechanical point of view. The results indic…

Nanocompositi e microcompositi: lavorabilità e proprietà meccaniche

BIODEGRADABLE BILAYER FILMS PREPARED BY CO-EXTRUSION

The sensitivity for reducing packaging waste drove academic and industrial efforts to search compostable or biodegradable bio-sourced polymeric materials. Multilayer systems represent a suitable strategy to obtain the required properties and to improve biopolymer performance. The aim of the current work is the coextrusion film blowing of a biodegradable bilayer film PLA/MaterBi with the purpose to overcome the drawbacks of the individual components.

Green and Integrated Wearable Electrochemical Sensor for Chloride Detection in Sweat

Wearable sensors for sweat biomarkers can provide facile analyte capability and monitoring for several diseases. In this work, a green wearable sensor for sweat absorption and chloride sensing is presented. In order to produce a sustainable device, polylactic acid (PLA) was used for both the substrate and the sweat absorption pad fabrication. The sensor material for chloride detection consisted of silver-based reference, working, and counter electrodes obtained from upcycled compact discs. The PLA substrates were prepared by thermal bonding of PLA sheets obtained via a flat die extruder, prototyped in single functional layers via CO2 laser cutting, and bonded via hot-press. The effect of co…

A simple method to interpret the rheological behaviour of intercalated polymer nanocomposites

Abstract Nanocomposites are a new class of polymer composites that exhibit an interesting combination of chemical, physical, thermal and mechanical properties. Only small amounts of nanofiller are sufficient to generate great variations of many properties. This work focuses on the rheological behaviour of the intercalated polymer nanocomposites in shear flow. The increase of the viscosity and the more pronounced non-Newtonian behaviour is interpreted simply considering the increase of volume of the inert phase caused by the intercalation of the macromolecules. Indeed, the volume of the intercalated tactoids increases with increasing the interlayer distance. On the other hand, the interlayer…

Effect of the elongational flow on morphology and properties of polypropylene/graphene nanoplatelets nanocomposites

Abstract In this work the effect of the presence of graphene nanoplatelets (GnP) on the morphology and mechanical properties of polypropylene/GnP nanocomposites has been investigated when these polymer systems are subjected to non-isothermal elongational flow in a melt spinning operation. The presence of the GnP magnifies the effect of the elongational flow. Indeed, the elastic modulus and the tensile strength of nanocomposites increases with the orientation more than that observed for the pure matrix. Moreover, the elongation at break increases at low values of the draw ratio for the nanocomposites, while, the matrix shows the expected decrease in deformability. These effects have been cor…

Effect of adding new phosphazene compounds to poly(butylene terephthalate)/polyamide blends. II: Effect of different polyamides on the properties of extruded samples

Poly(butylene terephthalate) (PBT) and a sample of polyamide have been melt processed in the presence of two new phosphazene compounds, namely 2,2-dichloro-4,4,6,6-bis[spyro(2',2"-dioxy-1',1"-biphenyl)]cyclotriphosphazene (2Cl-CP) and 2,2-bis(2-methoxy-4-methyleneoxy-phenoxy)-4,4,6,6-bis[spyro(2',2"-dioxy-1',1"-biphenyl)]cyclophosphazene (CP-2EPOX). The blends were prepared by using polyamide 6 (PA6) and polyamide 6,6 (PA66) in 25/75 and 75/25 w/w compositions by using a co-rotating twin-screw extruder. The materials have been completely characterized from a mechanical, rheological, and morphological point of view. The results indicate that the additives used cause an increase of the ruptur…

Pore size graded scaffold for selective cellular permeation

Preparation and characterization of polyamide 6/polyethylene blend-clay nanocomposites in the presence of compatibilisers and stabilizing system

Abstract Several compatibilising systems were added to high-density polyethylene (HDPE) and polyamide 6 (PA6) blends in the presence of an organically modified montmorillonite (OMM). All the blends were prepared by using a co-rotating twin-screw extruder and characterized by SEM, TEM and XRD analyses. In addition, the rheological behaviour and the mechanical properties – tensile and impact – were evaluated. The presence of OMM affects the dimensions of the polymeric phases in the blend but not their mutual adhesion, granted only by the compatibilisers. TEM, SEM and XRD analyses indicated that there is a strict correlation between the compatibilisation level and the final interlayer distance…

Polycaprolactone-based scaffold for oil-selective sorption and improvement of bacteria activity for bioremediation of polluted water: Porous PCL system obtained by leaching melt mixed PCL/PEG/NaCl composites: Oil uptake performance and bioremediation efficiency

A novel floatable and biodegradable sponge for the selective absorption of oil from water and potentially useful as cell carrier for bioremediation treatments was prepared in polycaprolactone (PCL). The eco-friendly process for fabricating the PCL sponge does not involve either synthetic routes or organic solvents, thus minimizing environmental hazard. In particular, the 3D porous materials have been prepared by mixing in the melt the polymer matrix with two water-soluble porogen agents (NaCl and PEG) and thereafter leaching the obtained PCL/NaCl/PEG composites in water. The PCL sponges here proposed are capable to remove different types of oily pollutants (up to 500 wt%), and were successf…

Proprietà di film antimicrobici a base di EVA preparati tramite filmatura in bolla

Rheological Response of Polyethylene/Clay Nanocomposites to Annealing Treatment

The rheological response of a polyethylene/clay nanocomposite to annealing treatment under air and nitrogen atmospheres was studied. The treatment influences the rheology of the nanocomposite significantly. In particular, the viscosity and the non-Newtonian behavior dramatically increase with annealing time, and a liquid-like/solid-like transition is observed. The annealed samples were characterized by ATR-FT-IR spectrometry and it was shown that a silicate-rich layer is formed on the surface of the nanocomposite. This result was confirmed by TEM images of bulk and surface of annealed samples. It was demonstrated that the formation of this coating is the main cause of the change of rheologi…

Incorporation of nisin in poly (ethylene-co-vinyl acetate) films by melt processing: a study on the antimicrobial properties

Both industry and academia have shown a growing interest in materials with antimicrobial properties suitable for food packaging applications. In this study, we prepared and characterized thin films of ethylene-co-vinyl acetate (EVA) copolymer with antimicrobial properties. The films were prepared with a film blowing process by incorporating a nisin preparation as an antimicrobial agent in the melt. Two grades of EVA containing 14 and 28% (wt/wt) vinyl acetate (EVA 14 and EVA 28, respectively) and two commercial formulations of nisin with different nominal activities were used. The effect of the nisin concentration also was evaluated. The films with the highest antimicrobial activity were th…

Processing-morphology-properties relationships in HDPE/PA6/Clay nanocomposites

A model for the prediction of the flow curves from interlayer distance and vice versa for intercalated polymer and polymer blend nanocomposites

In this work was proposed a simple model to predict the viscosity and the power law index from the interlayer distance and, vice versa, the interlayer distance from a single flow curve for intercalated polymer nanocomposites. This model cannot be applied to exfoliated nanocomposites or when other interactions are present in the systems.

Compatibilization of Polypropylene/Polyamide 6 Blend Fibers Using Photo-Oxidized Polypropylene.

The use of polyamide/polyolefin blends has gained importance and concern for years, but they also show some issues to be adequately addressed, such as the incompatibility between the two components. This is usually overcome by using suitable compatibilizers, typically based on functionalized polyolefins. However, there is only little information about the use of a degraded polyolefins to induce compatibilization. This is even truer, as far as polyamide 6/polypropylene (PA6/PP) blends are concerned. In this work, compatibilization of PA6/PP blends by using small amounts of photo-oxidized PP was investigated

Study on carvacrol and cinnamaldehyde polymeric films: mechanical properties, release kinetics and antibacterial and antibiofilm activities.

Polyethylene-co-vinylacetate (EVA) films with different concentrations (3.5 wt% and 7 wt%) of essential oil constituents, carvacrol or cinnamaldehyde, were prepared and characterized by mechanical, antibacterial and antibiofilm properties. The incorporation of the compounds into copolymer films affected their elastic modulus, tensile stress and elongation at break. Carvacrol and cinnamaldehyde act as plasticizers which reduce the intermolecular forces of polymer chains, thus improving the flexibility and extensibility of the film. The analysis of the surface characteristics demonstrated that essential oil constituents lowered the contact angle values without causing any remarkable variation…

Controllo della crescita e formazione di biofilm su film polimerici contenenti nisina

Nanofilled Thermoplastic-Thermoplastic Polymer Blends

Effect of annealing under different atmospheres on polyethylene-clay nanocomposite

Foto-ossidazione di film nanocompositi a base LDPE/EVA

Antimicrobial properties and release profile of monofilaments incorporating chlorhexidine for surgical applications

Degradation Behavior of Nanocomposite Polymer Blends

The usefulness of any material, including nanocomposite polymer blends, depends on its degradability and durability. Thus, this chapter reviews the status of the research on degradation of nanocomposite polymer blends and, in particular, on clay-nanocomposite polymer blends, paying particular attention to both the role of the filler and the role of the blend morphology and composition. The results of recent research indicate that the clay has two opposing effects on the thermal stability of a nanocomposite polymer blend: (1) a promoter effect of the polymer matrix degradation, which decreases the thermal stability, and (2) a barrier effect, which improves the thermal stability. Moreover, th…

Synthesis of a biocompatible aerogel based on graphene oxide and a modified polyethylene glycol

The synthesis and self-assembly of a 3D aerogel built by graphene oxide (GO) and a modified polyethylene glycol (PEG) was achieved by a multi-step synthetic procedure, involving the preparation of an amino-terminated PEG (PEG-NH2) and the subsequent coupling with GO by carbodiimide in water, exploiting the carboxyl and epoxy moieties of GO and –NH2 terminations of the biopolymer. The resulting nanohybrid hydrogel was successively converted into an aerogel via dialysis plus freeze-drying [1] and fully characterized. FTIR, Raman, XPS, XRD and BET measurements were performed to confirm the successful modification for each reaction step, while morphological, mechanical and hemolytic tests were …

Compatibilization of Polylactide/Poly(ethylene 2,5-furanoate) (PLA/PEF) Blends for Sustainable and Bioderived Packaging.

Despite the advantages of polylactide (PLA), its inadequate UV-shielding and gas-barrier properties undermine its wide application as a flexible packaging film for perishable items. These issues are addressed in this work by investigating the properties of melt-mixed, fully bioderived blends of polylactide (PLA) and poly(ethylene furanoate) (PEF), as a function of the PEF weight fraction (1–30 wt %) and the amount of the commercial compatibilizer/chain extender Joncryl ADR 4468 (J, 0.25–1 phr). J mitigates the immiscibility of the two polymer phases by decreasing and homogenizing the PEF domain size; for the blend containing 10 wt % of PEF, the PEF domain size drops from 0.67 &p…

Characterization of annealed LDPE/clay nanocomposites