Search results for "lactic acid"
showing 10 items of 660 documents
Integrated ternary bionanocomposites with superior mechanical performance via the synergistic role of graphene and plasma treated carbon nanotubes
2019
Abstract Herein, we prepared an integrated ternary bionanocomposite based on polylactic acid (PLA) as a host polymer and two different forms of carbon fillers, i.e. graphene nanoplatelets (GNPs) and carbon nanotubes (CNTs), used simultaneously at extremely low concentrations, relying on the synergistic effect of CNT and graphene nanoreinforcement and a novel, multi-step procedure to achieve a high level dispersion. The results indicated that this multi-step approach allows stiffness increments up to +66%, with simultaneous enhancement of tensile strength (up to +44%), and elongation at break (up to +36%) with respect to neat PLA, by adding an extremely low content (0.5 wt%) of a hybrid comb…
Mechanical behavior of polylactic acid/polycaprolactone porous layered functional composites
2016
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…
Polyaspartamide-based nanoparticles loaded with fluticasone propionate and the in vitro evaluation towards cigarette smoke effects
2017
This paper describes the evaluation of polymeric nanoparticles (NPs) as a potential carrier for lung administration of fluticasone propionate (FP). The chosen polymeric material to produce NPs was a copolymer based on α,β-poly(N-2-hydroxyethyl)-d,l-aspartamide (PHEA) whose backbone was derivatised with different molecules, such as poly(lactic acid) (PLA) and polyethylenglycol (PEG). The chosen method to produce NPs from PHEA-PLA-PEG2000 was the method based on high-pressure homogenization and subsequent solvent evaporation by adding Pluronic F68 during the process and trehalose before lyophilisation. Obtained colloidal FP-loaded NPs showed a slightly negative surface charge and nanometric d…
Lignocellulosic fillers and graphene nanoplatelets as hybrid reinforcement for polylactic acid: Effect on mechanical properties and degradability
2020
Abstract This work investigates the effect of adding relatively low amounts of graphene nanoplatelets (GNP) to a biocomposite based on polylactic acid (PLA) and a lignocellulosic filler achieved by grinding Posidonia Oceanica leaves (Posidonia flour, PF). The ternary composites were prepared by melt extrusion and characterized from a morphological and mechanical point of view. Furthermore, hydrolytic degradation tests were performed under acidic, neutral and alkaline environment up to 900 h. Density measurements enabled to assess the degree of intraphase, i.e. the capability of polymer macromolecules to enter the voids of PF and a modified Halpin-Tsai model was presented and used to fit exp…
Effect of graphene and fabrication technique on the release kinetics of carvacrol from polylactic acid
2019
Abstract Porous membranes and thin films containing poly-lactic acid (PLA), carvacrol (CRV) and graphene nanoplatelets (GNP) were fabricated by electrospinning and solvent casting at different formulations. The systems were characterized from a mechanical, morphological, calorimetric and spectroscopic point of view. CRV release as a function of time was studied and a mathematical model was used to fit and interpret the data in order to investigate the release mechanism. The results indicate that the incorporation of GNP generally determined a simultaneous strengthening, stiffening and toughening effect, while preserving a good ductility. Furthermore, integrating GNP allowed tuning the amoun…
Morphology and thermal properties of foams prepared via thermally induced phase separation based on polylactic acid blends
2012
Blends of poly-l-lactic acid with two different types of polylactic acid with different average molecular weights (50,000 and 175,000 g/mol, respectively) in different proportions (90/10, 80/20 and 70/30) were utilized in order to produce biodegradable and biocompatible scaffolds for soft tissue engineering applications. The scaffolds were produced via thermally induced phase separation starting from ternary systems where dioxane was the solvent and water the non-solvent. Morphology (average pore size and interconnection) was evaluated by scanning electron microscopy. Foams apparent density was also evaluated (porosity ranges from 87% to 92%). Moreover, a differential scanning calorimetry …
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…
X-ray micro-tomography based FEM modelling of hygroexpansion in PLA composites reinforced with birch pulp fibres
2017
This article presents a microscale modelling approach coupled with X-ray computed micro-tomography for the evaluation of material properties of polylactic acid (PLA) reinforced by birch pulp fibers under the effect of moisture. The results in terms of elastic moduli and hygroexpansion deformation were found in good agreement with the measurements taken at different levels of water uptake.
Core-shell PLA/Kef hybrid scaffolds for skin tissue engineering applications prepared by direct kefiran coating on PLA electrospun fibers optimized v…
2021
Abstract Over the recent years, there is a growing interest in electrospun hybrid scaffolds composed of synthetic and natural polymers that can support cell attachment and proliferation. In this work, the physical and biological properties of polylactic acid (PLA) electrospun mats coated with kefiran (Kef) were evaluated. Gravimetric, spectroscopic (FTIR-ATR) and morphological investigations via scanning electron microscopy confirmed the effective formation of a thin kefiran layer wrapped on the PLA fibers with an easy-tunable thickness. Air plasma pre-treatment carried out on PLA (P-PLA) affected both the morphology and the crystallinity of Kef coating as confirmed by differential scanning…
Effect of hydroxyapatite concentration and size on morpho-mechanical properties of PLA-based randomly oriented and aligned electrospun nanofibrous ma…
2019
The growing demand for nanofibrous biocomposites able to provide peculiar properties requires systematic investigations of processing-structure-property relationships. Understanding the morpho-mechanical properties of an electrospun scaffold as a function of the filler features and mat microstructure can aid in designing these systems. In this work, the reinforcing effect of micrometric and nanometric hydroxyapatite particles in polylactic acid-based electrospun scaffold presenting random and aligned fibers orientation, was evaluated. The particles incorporation was investigated trough Fourier transform infrared spectroscopy in attenuated total reflectance. The morphology of the nanofibers …