Reprocessing of PLA/graphene nanoplatelets nanocomposites

2017

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…

Polysaccharide nanocrystals as fillers for PLA based nanocomposites

2016

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…

Structure-properties relationships in melt reprocessed PLA/hydrotalcites nanocomposites

2017

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…

Photooxidation Behavior of a LDPE/Clay Nanocomposite Monitored through Creep Measurements

2017

Creep behavior of polymer nanocomposites has not been extensively investigated so far, especially when its effects are combined with those due to photooxidation, which are usually studied in completely independent ways. In this work, the photooxidation behavior of a low density polyethylene/organomodified clay nanocomposite system was monitored by measuring the creep curves obtained while subjecting the sample to the combined action of temperature, tensile stress, and UV radiation. The creep curves of the irradiated samples were found to be lower than those of the non-irradiated ones and progressively diverging, because of the formation of branching and cross-linking due to photooxidation. …

Using Taguchi method for the optimization of processing variables to prepare porous scaffolds by combined melt mixing/particulate leaching

2017

Synthetic biopolymers have made significant inroads into the development of devices for tissue regeneration. In this context, a challenge is the achievement of appropriate properties mimicking the natural extracellular matrix by fabricating scaffolds presenting mechanical properties, specific surface, porosity and pore interconnection adequate for the final application. This study involved a systematic procedure based on Taguchi method for parameters optimization of melt mixing/particulate leaching combined processes aiming to enhance the performance of the scaffolds. In particular, it was evaluated the effect of time and temperature of melt mixing of the poly(lactic acid) matrix with two w…

Green Nanocomposites-Based on PLA and Natural Organic Fillers

2017

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…

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

2016

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…

Effect of Elongational Flow and Polarity of Organomodified Clay on Morphology and Mechanical Properties of a PLA Based Nanobiocomposite

2016

Abstract In biodegradable polymer world nanobiocomposites represent a new group of materials filled with inert nanoparticles that shows very interesting properties and the biodegradability of the matrix. In this work we have studied the effect of the polarity of the organomodified montmorillonite and of the elongational flow on the morphology and the rheological and mechanical properties of a new nanobiocomposite with a matrix of biodegradable PLA based blend. The elastic modulus enhances in presence of the nanofiller and this increase is larger and larger with the increment of the orientation. The tensile strength does not show any significant change at the same level of orientation. Moreo…

Development of polymeric functionally graded scaffolds: a brief review.

2016

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

2018

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…

Degradation and Recycling of Films Based on Biodegradable Polymers: A Short Review

2019

The environmental performance of biodegradable materials has attracted attention from the academic and the industrial research over the recent years. Currently, degradation behavior and possible recyclability features, as well as actual recycling paths of such systems, are crucial to give them both durability and eco-sustainability. This paper presents a review of the degradation behaviour of biodegradable polymers and related composites, with particular concern for multi-layer films. The processing of biodegradable polymeric films and the manufacturing and properties of multilayer films based on biodegradable polymers will be discussed. The results and data collected show that: poly-lactic…

In-process material characterization at constant extrusion conditions: application to clay/PLA bionanocomposites

2017

The authors developed a prototype modular small-scale single / twin-screw extrusion system, with outputs in the range of grams/hour, coupled to a rheo-optical slit die. This experimental set-up is adequate to measure shear viscosity and normal-stress differences and perform optical measurements

SVILUPPO DI MATERIALI INNOVATIVI NANOSTRUTTURATI A BASE DI BIOPOLIMERI PER APPLICAZIONI IN IMBALLAGGI

I materiali nanocompositi hanno attirato l’interesse della comunità scientifica e industriale degli ultimi decenni grazie alle proprietà straordinarie che la matrice polimerica acquista semplicemente a seguito dell’incorporazione di una carica nanostrutturata al suo interno. Le nanotecnologie sono così attraenti perché mediante l’aggiunta di solo poche percentuali in peso di una carica nanostrutturata, consentono di utilizzare le classiche tecniche di lavorazione dei polimeri tradizionali e di conseguenza permettono la preparazione di materiali innovativi a costi contenuti. Poiché oltre al potenziamento delle proprietà iniziali i materiali nanostrutturati possono anche acquisirne di nuove, …

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

2016

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.

BIODEGRADABLE BILAYER FILMS PREPARED BY CO-EXTRUSION

2017

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.