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Biodegradable polymers are highly sought after as they have the potential to reduce the issue of plastic waste and eventually lead to a circular economy. Yet, conciliating eco-friendliness with competitive properties is often challenging. Polymerization and processing techniques have been developed and optimized to improve such factors. Some of the common polymerization methods to obtain such materials are condensation, ring-opening, addition, and biocatalytic-assisted polymerization. Alongside that, processing techniques such as melt mixing/extrusion, solution castings, compression, and injection molding have also been employed for the manufacture of biodegradable polymers. While these traditional techniques are viable routes to market, there is still the need to further improve their properties to make them comparable to their petrochemical-based counterparts. To assist with that, the production of composites and blending techniques are facile approaches that demonstrated promising improvements in their properties. Based on these aspects, this review is aimed at discussing the main types of biodegradable polymers, followed by the compositing approaches reported in the recent literature, their structure-property relationships, and biodegradability mechanisms. The first section provides an introductory overview of biodegradable polymers and their composites. The second section focuses on the most prominent polymers used in the industry. Furthermore, the fabrication techniques, along with their property and application relationships are provided with an emphasis on mechanical reinforcements and the biomedical field. Finally, some future perspectives are given to clarify some of the known challenges and, possibly, provide some insights for the reader to develop novel ideas. [ABSTRACT FROM AUTHOR]

Several solutions have been presented to minimize the environmental impact generated by polymers produced from petroleum resources. This work produced a biopolymer using glycerol, starch (<5) and macaúba epicarp fiber (10–15–20–25–30%) as reinforcement. The interaction of glycerol with starch was favored by the addition of acetic acid (CH3COOH). The pH was adjusted with sodium hydroxide (NaOH) at a concentration of 0.1 mol·L−1. The characterization was carried out through scanning electron microscopy (SEM), infrared reflectance—FTIR, water solubility, biodegradability and technological properties. Through the results obtained in this work, it is observed that the tensile strength and modulus of elasticity are influenced by the addition of the fiber concentration; the sample that received a 30% addition presented 19.17 MPa and 348.12 MPa, respectively. All samples showed low solubility in water and low density, in addition to a high rate of degradability in soil with mass loss corresponding to 59% over a period of three months. The results of this investigation are satisfactory for the production of materials that can be used in everyday life, replacing conventional plastic. [ABSTRACT FROM AUTHOR]

The aim of the given work was to design new ecologically friendly polymer materials modified by derivatives of coal. An overview of the current trend in the development, production and application of efficient environmentally friendly polymer materials and composites is given. The main ways of hybrid modification of environmentally friendly polymeric composite for obtaining effective products based on them are presented. It is shown that it is promising to obtain environmentally friendly polymeric materials based on coffee waste using hybrid modifiers in the form of humic substances. Optimization studies have been conducted to determine the most effective composition of new environmentally friendly polymeric materials based on bioplastics "OK compost HOME" and coffee waste modified with humic substances. It was found that filling the bioplastic "OK compost HOME" with such coffee waste as coffee husk is more effective as with coffee grounds. It was found that the optimal content is 60 % mass coffee husk, that was modified by humic substances (2 % mass). [ABSTRACT FROM AUTHOR]

Environmental pollution by synthetic polymers is a global problem and investigating substitutes for synthetic polymers is a major research area. Starch can be used in formulating bioplastic materials, mainly as blends or composites with other polymers. The major drawbacks of using starch in such applications are water sensitivity and poor mechanical properties. Attempts have been made to improve the mechanical properties of starch-based blends and composites, by e.g., starch modification or plasticization, matrix reinforcement, and polymer blending. Polymer blending can bring synergetic benefits to blends and composites, but necessary precautions must be taken to ensure the compatibility of hydrophobic polymers and hydrophilic starch. Genetic engineering offers new possibilities to modify starch inplanta in a manner favorable for bioplastics applications, while the incorporation of antibacterial and/or antioxidant agents into starch-based food packaging materials brings additional advantages. In conclusion, starch is a promising material for bioplastic production, with great potential for further improvements. This review summarizes the recent advances in starch-based blends and composites and highlights the potential strategies for overcoming the major drawbacks of using starch in bioplastics applications. [ABSTRACT FROM AUTHOR]

This work presents the development and characterization of biodegradable polymeric composites based on natural rubber and protein waste from finished post-consumer leather. Protein waste is cryogenically ground to min. 500 nm, functionalized by a mechanical process at temperature with potassium oleate (5%) and mixed in the composite in various proportions (5, 10, 20, 30, 50%). This composite will be made into a low-density product, with low cost, recovery and reuse of waste, and last but not least, biodegradable. The methodology for making the new materials involves the following steps: sorting waste, grinding, functionalization and compounding. These operations are easy to manage and do not involve new equipment. Compounding, the most important operation, will be carried out on a roller and the mixtures will be processed into finished products by compression in an electric press. The tested biodegradable composites were structurally and physico-mechanically characterized. Waste transformation (ground and functionalized) into new value-added products will lead to remarkable improvements in the life cycle of raw materials and the sustainable use of this waste, contributing to sustainability, improving eco-efficiency and economic efficiency and reducing the “pressure” of waste on the environment. [ABSTRACT FROM AUTHOR]

There is an increased interest in the scientific community regarding the use of bio-based polymers in composites, as combining these matrices with natural fibres produces "green composites" or "bio-composites". At present, natural-fibre-reinforced-composites (NFRCs) are seen as realistic alternatives to synthetic- (e.g., glass) fibre-reinforced composites in many applications. [Extracted from the article]

The addition of natural scraps to biodegradable polymers has gained particular interest in recent years, allowing reducing environmental pollution related to traditional plastic. In this work, new composites were fabricated by adding 10% or 20% of Hedysarum coronarium (HC) flour to Poly (lactic acid) (PLA). The two formulations were first produced by twin screw extrusion and the obtained filaments were then employed for the fabrication of composites, either for compression molding (CM) or by fused deposition modeling (FDM), and characterized from a morphological and mechanical point of view. Through FDM it was possible to achieve dense structures with good wettability of the filler that, on the contrary, cannot be obtained by CM. The results indicate that the filler effectively acts as reinforcement, especially for FDM composites. The most remarkable enhancement was found in the flexural properties (+100% of modulus and ultimate strength), followed by tensile resistance and stiffness (+60%) and impact strength (+50%), whereas a moderate loss in tensile deformability was observed, especially at the highest loading. By adding HC to the polymeric matrix, it was possible to obtain a green, high-performance, and cost-effective composite, which could find applications for the fabrication of panels for furniture or the automotive industry. [ABSTRACT FROM AUTHOR]

The proliferation of petroleum-derived plastics has led to environmental concerns, prompting the exploration of sustainable alternatives. This study deals with the development of natural polymeric composite materials that can be used as alternatives to conventional plastics. In particular, biocomposite films were prepared by hot pressing a blend of carrot pomace (CP) with 10, 30 and 50 wt% of two vegetable proteins: wheat gluten (Gn) and zein (Z), for the optimization of the final properties of the developed biomaterials. The resulting composites exhibit improved physicochemical, morphological, and thermal properties and provide enhanced water resistance compared to CP-only bioplastics, while in particular, the ones prepared with Gn, exhibited also improved optical and mechanical properties, making Gn composites best candidates for a larger number of applications. Further optimization was achieved by adding 10 wt % polyglycerol plasticizer to the CP-50 wt% Gn composites, resulting in even better mechanical and oxygen barrier properties. These biocomposites show great potential for food packaging, offering mechanical resistance (elastic modulus of 244.9 ± 25.3 MPa and tensile strength of 10.1 ± 0.7 MPa), flexibility (elongation at break of 24.7 ± 5.7%), high transparency and optical clarity, effective UV-blocking in the 200–350 nm range, excellent antioxidant activity (3.4 μmol Trolox/g) and water vapor (1.3 × 10−9 g s−1 m−1 Pa−1) and oxygen (296.1 ± 1 cm3 μm m−2 day−1 atm−1) barrier properties. Additionally, they exhibit low migration of components into food simulants (6.7 ± 0.6 mg dm−2) and fast biodegradation in soil (83% after 30 days). The findings reported in this manuscript motivate the adoption of eco-friendly materials and represent a significant step towards a sustainable future. [Display omitted] • Biocomposite films were obtained by blending carrot pomace (CP) with vegetable proteins. • CP + Zein and CP + Gluten biocomposite films exhibited superior properties than CP films. • Vegetable proteins provided enhanced water resistance compared to CP-only bioplastics. • Biocomposite films with Gn exhibited improved optical and mechanical properties of CP. • Biocomposite films showed high transparency, antioxidant capacity, and fast biodegradability. [ABSTRACT FROM AUTHOR]

The relevance of the study is conditioned by the fact that increased consumption of synthetic polymers leads to an increase in environmental pollution due to the long decomposition time of plastic waste. As a result, it is necessary to develop polymer composites based on a biodegradable polymer matrix, and to improve the performance properties of finished plastic products, it is necessary to purposefully select cheap and affordable inorganic fillers. Thus, the purpose of this study is to investigate the regularities in the generation of a spatially structured polymer matrix under UV irradiation of polylactide-based composites filled with aluminosilicate microspheres (ASM). The leading approach to the given problem is to melt polymer composites of various compositions and to determine the physical, mechanical, and thermophysical characteristics of the prototypes, including the supermolecular structure of the polymer matrix under the influence of ultraviolet irradiation. The study suggests that the filling of polylactide with ASM particles leads to an increase in the elastic modulus, a decrease in the strength at static rupture and resistance to dynamic destructive effects, as well as heat resistance. Small aluminosilicate microspheres, when added to polylactide, perform the function of nucleation and, even with a small content, increase the crystallinity degree by 3.7 percentage points. In the range of ASM content from 1 pph to 10 pph, the absolute value of the crystallinity degree practically does not depend on the filler concentration in the polymer composite. UV (ultraviolet) irradiation in the presence of air oxygen initiates the thermooxidative destruction of polylactide and leads to the establishment of a spatially structured polymer phase using the electrostatic intermolecular interaction of additionally formed oxygen-containing functional groups in macrochains, as well as partial intermolecular crosslinking during recombination of macroradicals. The establishment of spatial structures in the polymer matrix under UV irradiation determines an increase in the resistance of experimental samples to thermal effects. It is manifested in an increase in the bending temperature under load by 7-10 percentage points, a decrease in the crystallinity degree by 1.2-2.6 percentage points, a decrease in the fluidity of the meltage and also an increase in the glass transition and melting temperature. The materials of the study are of practical value for the development of biodegradable composites based on polylactide filled with inorganic components. [ABSTRACT FROM AUTHOR]

• Biodegradable Silk fibroin - PSADT based composite coatings were grown by MAPLE. • We designed and used working protocol and in flux-degradation setup for thin coatings. • Biocompatible polymeric coatings with adjusted degradability were tested for medical appl. • Increasing PSADT ratios improve persistence of the composite biopolymeric coatings. • Composits with 1:1 SF-PSADT ratios approximate a zero order degradation behavior. We report here on the bio-polymeric composite coatings deposition for medical applications, demanding adjustable biodegradability, by the Matrix Assisted Pulsed Laser Evaporation, a sterile laser tool technology, tested for degradation, wettability and bio-compatibility preservation. The specific FTIR bands of both materials indicated stoichiometric deposition of composite coatings, and meanwhile suggested the predominant presence of amorphous SF phase, as also validated by XRD, with low intensity maxima emerging from the amorphous matrix. Concerning the PSADT component, XRD clearly evidenced its specific crystalline contribution. The degradation behaviour in simulated body fluid at 37 °C in dynamic regime was studied as first step of applicability in potential sustained controlled release applications (and/or degradable implanted electronics). Weighing measurements of degraded samples confirmed slower degradation tendency with increasing initial PSADT amount. They also revealed approximately zero order SBF-degradation for 1:1 SF-PSADT ratio. The in vitro assays showed uniform spreading of human mesenchymal stem cells on all synthesized coatings. [ABSTRACT FROM AUTHOR]

Bio-degradability and sustainability have become major objectives in the field of materials engineering. Due to this, the utilisation of natural reinforcement is gaining immense attention among composite researchers. Among the different composites, polymeric composites are used as structural components. In the present day investigations, bio-elements are majorly utilized as reinforcements due to their properties and bio-degradability. Although polymeric components are manufactured in the shape of the final component, they need secondary processing to make it suitable for assembly. Hence, a review on machining and associated investigations on bio-composites would help the composites industries and upcoming researcher to know the scope of research and for selection of apt machining conditions. This review gives a detailed insight on the various machinability factors and their measurement, influence of machining parameters on the machinability and optimum conditions during machining of bio-composites. In addition, this review also presents about the importance of bio-fibre under various situations of machining and untraditional machining methods used for bio-composites. [ABSTRACT FROM AUTHOR]

Poly(L-lactic acid) (PLLA) is a popular biodegradable polymer, but the accumulated acid production by degradation is a bottleneck for its extended utilization. In this study, chitosan microspheres (CSMs) were introduced into PLLA porous matrices to manipulate the acid microclimate from PLLA degradation. In vitro and in vivo degradation were, respectively, performed in PBS and implanted into rat’s subcutaneous. The results indicated that pH of CSMs/PLLA composites remained stable of around 7.50 in vitro until six weeks. With the increasing of CSMs, mass loss, water absorption of the composites increased, while Mv of PLLA decreased during in vitro test. Furthermore, CSMs/PLLA composites degradation in vivo could be speeded by the introduction of CSMs via obvious morphological destroy under H&E staining observation. These results indicated that incorporation of CSMs not only buffered the acidic microclimate but also improved the degradation of PLLA. The tunable degradation behavior and moderate degradation microclimate of CSMs/PLLA composites developed in the study would provide benefits for its biomedical application. [ABSTRACT FROM AUTHOR]

Mimicking the three-dimensional (3D) biological structure of native tissues and organs has remained a challenge for tissue engineering. The current use of hydrogels for intervertebral disc (IVD) repair is not ideal for insufficient mechanical properties. To overcome this limitation, we combine the excellent mechanical performance of poly(lactic acid) (PLA) with the biocompatibility and bioprintability of gellan gum-poly (ethylene glycol) diacrylate (GG-PEGDA) double network hydrogel to meet the necessary requirement of IVD regeneration. The cell-laden constructs were fabricated using 3D bioprinting technology. Mechanical and degradation properties of the dual printed scaffolds can be regulated by controlling the infill patterns and density of the PLA frameworks. Bone marrow stromal cells co-printed into the PLA/GG-PEGDA scaffolds remained high viability and showed excellent spreading within the hydrogels. Considering positive biocompatibility accompanied with suitable mechanical properties, this hybrid scaffolds have the potential to assist IVD regeneration. [ABSTRACT FROM AUTHOR]

Biodegradable composites based on polylactide (PLA) and starch are obtained via solid‐phase mixing under conditions of shear deformation. The mechanical properties and biodegradability of composites under action of mold fungi as well as during exposure in soil are investigated. Using the scanning electron microscopy, the comparative study of the morphology of the initial samples and samples after biodegradation is carried out and the formation of structural defects resulting in sample destruction followed by fragmentation is revealed. The influence of PEG on mechanical properties and biodegradation process of the composites is shown. The analysis of composites by FTIR spectroscopy allows the estimation of the change in the PLA crystallinity and morphology of the film composites during the biodegradation in soil. The appearance of starch on the surface of films after exposure in soil enables a mechanism of biodegradation to be proposed. [ABSTRACT FROM AUTHOR]

Bio-based plastics, such as Wood-Plastics Composites (WPC), represent a new generation of sustainable building materials. They contain up to 80% of renewable resources and comparatively less fossil-based plastics. Reportedly, WPC products preserve crude oil for upcoming generations. However, WPC suffers from a moderate consumer acceptance due to its plastics-like appearance and a lack of differentiation to low-price plastics. Obviously, WPC hardly takes advantage of its environmental opportunity. This paper examines to what extend WPC could benefit from an eco-label as a means of self-regulation and how internalization acts in favor of society. An economic impact analysis is carried out using basic knowledge from a comprehensive literature research about eco-labeling effects on market allocation and welfare. The current WPC-market was subject of further investigations to find out whether a WPC eco-label has a welfare-increasing potential. The analysis revealed that labels are currently in use for differentiation among WPC products which yields higher profits and thus reduces consumer surplus. From social perspective it would be more beneficial to employ such labels for better distinguishing between pure plastics and WPC. In such a case a WPC eco-label would perfectly reduce externalities from crude oil plastics production and this goes along with a growing demand for green-plastics and higher willingness-to-pay of eco-aware consumers which is beneficial for the development of a green building market. Finally, social welfare is most likely to be higher than without labeling even if producer profit increased as well. Nevertheless, total welfare is expected to be maximal only if a public regulator prevents the industry from profit maximization which, however, is not recommendable for the investment-intensive WPC-branch. [ABSTRACT FROM AUTHOR]

A biodegradable polylactic acid composite containing tricalcium phosphate microsphere was fabricated. The composite exhibited enhanced biocompatibility and a well-interconnected porous structure that enabled tissue ingrowth after degradation. The tricalcium phosphate microspheres had an average size of 106 f 43 lam and were incorporated into the polylactic acid matrix using a high-shear mixer. The resulting bioactivity and hydrophilicity were enhanced to levels comparable to those of a polylactic acid composite containing tricalcium phosphate powder, which is a well-known material used in the medical field. An accelerated 30-day degradation test in HCl revealed successful generation of an open porous structure with -- 98% interconnectivity in the polylactic acid -- tricalcium phosphate microsphere composite, demonstrating the potential of this material to induce enhanced osseointegration in the later stage of bone regeneration. The early stage osseointegration was also evaluated by implanting the composite in vivo using a rabbit femoral defect model. After 16 weeks of implantation, the bone-to-implant contact ratio of the polylactic acid -- tricalcium phosphate microsphere composite was enhanced owing to tissue ingrowth through the generated pores near the surface. [ABSTRACT FROM AUTHOR]

Bio-based polymer foams have been gaining immense attention in recent years due to their positive contribution towards reducing the global carbon footprint, lightweighting, and enhancing sustainability. Currently, polylactic acid (PLA) remains the most abundant commercially consumed biopolymer, but suffers from major drawbacks such as slow crystallization rate and poor melt processability. However, blending of PLA with a secondary polymer would enhance the crystallization rate and the thermal properties based on their compatibility. This study investigates the physical and compatibilized blends of PLA/poly (butylene succinate-co-adipate) (PBSA) processed via supercritical fluid-assisted (ScF) injection molding technology using nitrogen (N2) as a facile physical blowing agent. Furthermore, this study aims at understanding the effect of blending and ScF foaming of PLA/PBSA on crystallinity, melting, and viscoelastic behavior. Results show that compatibilization, upon addition of triphenyl phosphite (TPP), led to an increase in molecular weight and a shift in melting temperature. Additionally, the glass transition temperature (Tg) obtained from the tan curve was observed to be in agreement with the Tg value predicted by the Gordon-Taylor equation, further confirming the compatibility of PLA and PBSA. The compatibilization of ScF-foamed PLA-PBSA was found to have an increased crystallinity and storage modulus compared to their physically foamed counterparts. [ABSTRACT FROM AUTHOR]

The plasticization of stereocomplex polylactide (scPLA) with poly(propylene glycol) (PPG) is described. The poly( L-lactide) (PLLA), poly(D-lactide) (PDLA) and PPG were completely blended in chloroform before film casting to prepare scPLA/PPG blend films. The PLLA/PDLA ratio was fixed at 50/50 (w/w). The PPG blending enhanced the stereocomplex formation of the scPLA films. The stereocomplex crystallinities of the scPLA films increased as the PPG blend ratio increased, the PPG molecular weight decreased and the PDLA molecular weight decreased. The PPG blending significantly decreased the T and film transparency, and improved the elongation at break of the scPLA films. The results indicated that the PPG blending had an effect on the stereocomplexation and it improved the flexibility of the scPLA films. [ABSTRACT FROM AUTHOR]

The green blends of an ionic liquid, 1-ethyl-3-propylimidazolium bis(trifluoromethanesulfonyl) imide {[EPrI][TFSI]}, and a biodegradable polymer, poly(3-hydroxybutyrate) (PHB), were investigated in this study. The influence of an ionic liquid on the crystallization behaviors of a biodegradable polymer was explored. In the blends, the presence of [EPrI][TFSI] decreased the Tg and Tm of PHB. Incorporating [EPrI][TFSI] in the blends reduced the degree of crystallinity of PHB, inferring that the [EPrI][TFSI] weakened the crystallization of PHB. It further showed retarded isothermal and non-isothermal crystallization for PHB with the presence of [EPrI][TFSI]. The smaller K and 1/t0.5 estimated by the Avrami equation for the blends indicated that [EPrI][TFSI] weakened the isothermal crystallization of PHB with exhibiting the slower crystallization rate. The present study also discussed non-isothermal crystallization of the blends. We found that the Mo model, which is generally used to discuss the non-isothermal crystallization, adequately described the non-isothermal behaviors of the [EPrI][TFSI]/PHB blends. By increasing the [EPrI][TFSI] content, the rate-related parameter F(T) systematically increased, inferring a decreased crystallization rate of PHB with the addition of [EPrI][TFSI] in the blends. The FTIR results suggested an ion-dipole interaction between [EPrI][TFSI] and PHB. This proposes the occurrence of possible complexation between [EPrI][TFSI] and PHB. [ABSTRACT FROM AUTHOR]

The study focuses on the development of novel Aloe vera based polymeric composite films and antimicrobial suture coatings. Polyvinyl alcohol (PVA), a synthetic biocompatible and biodegradable polymer, was combined with Aloe vera, a natural herb used for soothing burning effects and cosmetic purposes. The properties of these two materials were combined together to get additional benefits such as wound healing and prevention of surgical site infections. PVA and Aloe vera were mixed in a fixed quantity to produce polymer based films. The films were screened for antibacterial and antifungal activity against bacterial (E. coli, P. aeruginosa) and fungal strains (Aspergillus flavus and Aspergillus tubingensis) screened. Aloe vera based PVA films showed antimicrobial activity against all the strains; the lowest Aloe vera concentration (5%) showed the highest activity against all the strains. In vitro degradation and release profile of these films was also evaluated. The coating for sutures was prepared, in vitro antibacterial tests of these coated sutures were carried out, and later on in vivo studies of these coated sutures were also performed. The results showed that sutures coated with Aloe vera/PVA coating solution have antibacterial effects and thus have the potential to be used in the prevention of surgical site infections and Aloe vera/PVA based films have the potential to be used for wound healing purposes. [ABSTRACT FROM AUTHOR]

The ternary blends consisting of biodegradable polymer-based ternary blends composites were prepared by the solution blending method with glutaraldehyde. Prepared ternary blends were characterized by Fourier transform infrared spectroscopy, X-ray diffraction, thermogravimetric analysis, and differential scanning calorimetry. Subsequently, the adsorbent activity for heavy metal, chromium, was estimated in terms of the existent initial concentration, adsorbent dose, contact time, and pH. The adsorption study was performed for the pH ranging from pH 4.0 to 8.0. It was observed that the sorption efficiency, increased with increasing the pH of the solution from 4.0 to 5.5. At low pH values of the solution, the amine groups were propagated to various degrees, reducing the number of binding sites available for metal ion uptake so that the extent of chromium uptake is low in the high concentrations of protons. Moreover, the protonation of amine groups is induced an electrostatic repulsion of cations. When the pH of the solution was more than 5.5, the sorption rate began to decrease. Besides, the quantity of adsorbate on absorbent was fitted as a function in Langmuir and Freundlich isotherm. The sorption kinetics were tested for pseudo first- and pseudo second-order reactions. The kinetic experimental data correlated with the second-order kinetic model and rate constants of sorption for kinetic models were calculated and accordingly, the correlation coefficients were obtained. The investigation emphasized that the composite was very effective for the adsorption of Cr (VI). [ABSTRACT FROM PUBLISHER]

The development of new plant fibre composites is a key point in the development of semi-structural biodegradable or biobased parts, especially for automotive applications. The aim of this original and innovating work is to study, at different scales, the recycling ability of a fully biodegradable L-Poly-(lactide)-Poly-(butylene-succinate)-flax (PLLA-PBS-flax) biocomposite. The biocomposites were manufactured by twin-screw extrusion followed by injection moulding, then the recycling behaviour was studied during successive injection moulding cycles. Firstly, we investigated the length of the flax fibre after compounding and injection, as well as the cell wall stiffness and hardness, by in-situ nanoindentation tests. Secondly, we focused on the effects of recycling on thermal, rheological and tensile properties. We highlighted a severe evolution of the cell wall properties, especially concerning the polysaccharidic matrix after the first thermal cycle, nanoindentation properties remaining quasi-stable after this first drop. Furthermore, the biocomposites did not show any significant evolution of their mechanical performances during cycle three or four of the first injection cycles; after this plateau, the tensile strength and strain as well as impact energy were significantly altered due to the conjugated fibre length decrease and degradation of the PLLA, the latter being emphasized when the flax fibre is embedded. Nevertheless, this fully biodegradable composite exhibits a suitable recycling behaviour for 3 or 4 cycles, which is sufficient for industrial applications. [ABSTRACT FROM AUTHOR]

Biodegradable polymers—polyethylene oxide and poly (ϵ-caprolactone)—were melt extruded withβ-tricalcium phosphate. Breakdown analysis revealed that the percentage increase in bioceramic caused a prolonged degradation rate, with samples containing 20 wt%β-tricalcium phosphate losing significantly less weight over time in comparison to the control sample. Compression testing of samples following submission in aqueous environments revealed the composites exhibited enhanced strength with increasing bioceramic loading. The mechanical properties were significantly reduced over a period of 5 weeks. It was found that hot-melt extrusion ofβ-tricalcium phosphate is a viable and effective method of producing novel composite scaffolds with potential for regenerative medicine applications. [ABSTRACT FROM PUBLISHER]

This work presents a new technique for producing a slow-release fertiliser with bioplastic polymer coating. Poly(lactic acid) (PLA) was blended with granular NPK fertiliser and empty fruit bunch (EFB) fibres using extrusion technique. The polymer coatings were characterised using thermal gravimetric analyser (TGA) and diffraction scanning calorimetry (DSC). The PLA and EFB fibres complemented each other in terms of their thermal stability in the BpF composites. A homogenous BpF blend was observed under a scanning electron microscope (SEM). In biodegradation the percentages of weight loss for PLA/EFB/NPKC1 and PLA/EFB/NPKC2 were higher due to the presence of EFB fibres, which were 64.3% and 76.3%, respectively. [ABSTRACT FROM AUTHOR]

Microwave initiated grafting of itaconic acid was carried out on guaran polysaccharide to get a crosslinked network of guaran–itaconic acid. Different reaction parameters were optimized for the graft copolymerization of itaconic acid on guaran to get the candidate polymer with maximum percentage swelling. Conducting interpenetrating polymer network (IPN) was prepared by aniline absorption in the semi-IPN network by two-step aqueous polymerization. Crosslinked structure was characterized by Fourier transform infra-red spectroscopy (FTIR), thermogravimetric analysis (TGA) and scanning electron microscopy (SEM). Biodegradation of synthesized hydrogels was studied by soil burial and composting methods and monitored by FTIR and SEM techniques. Conducting interpenetrating polymer network composite hydrogels were studied for the adsorptive removal of methylene blue dye. Pseudo first and pseudo second order kinetics models were used to describe the adsorption kinetics of dye removal. [ABSTRACT FROM AUTHOR]

Biodegradable composite films were prepared using two renewable resources based biopolymers, agar and lignin alkali. The lignin was used as a reinforcing material and agar as a biopolymer matrix. The effect of lignin concentration (1, 3, 5, and 10 wt%) on the performance of the composite films was studied. In addition, the mechanical, water vapor barrier, UV light barrier properties, FE-SEM, and TGA of the films were analyzed. The agar/lignin films exhibited higher mechanical and UV barrier properties along with lower water vapor permeability compared to the neat agar film. The FTIR and SEM results showed the compatibility of lignin with agar polymer. The swelling ratio and moisture content of agar/lignin composite films were decreased with increase in lignin content. The thermostability and char content of agar/lignin composite films increased with increased lignin content. The results suggested that agar/lignin films have a potential to be used as a UV barrier food packaging material for maintaining food safety and extending the shelf-life of the packaged food. [ABSTRACT FROM AUTHOR]

The natural fiber reinforced biodegradable polymer composites were prepared with short sisal fiber as reinforcement in poly lactic acid (PLA) matrix. The sisal fiber is treated with 10% NaOH followed by H2O2. The composites were prepared with untreated and treated short sisal fibers at different weight proportions up to 25% in PLA matrix and investigated for mechanical and degradation properties. The results showed that the composite with treated fiber at 20% fiber loading has shown 30% and 8% higher tensile strength than neat PLA and untreated sisal/PLA composite, respectively. The flexural strength of treated sisal fiber composite at same weight fraction was 17% higher than that of plain PLA. The impact strength of composite with untreated fibers at 25% fiber loading was 107% high compared to that of neat PLA whereas the impact strength of treated sisal composite was reduced with increased fiber loading. The water absorption was high for untreated sisal/PLA composite compared to all other composites in the present study. Untreated sisal/PLA composite has high thermal degradation temperature compared to composite with treated fibers but lower than that of pure PLA. The enzymatic environment has increased the rate of degradation of composites. Surface morphology of tensile fractured and soil degraded surfaces of the composites were observed using scanning electron microscopy. [ABSTRACT FROM AUTHOR]

The non-isothermal crystallization of biodegradable thermoplastic matrix (Mater-Bi, MB) and traditional thermoplastic (polypropylene, PP) blends was studied using differential scanning calorimetry (DSC). Hemp fibres were used as filler, and maleic anhydride functionalized polypropylene (PP*) was employed as compatibilizer. MB forms immiscible blends with PP. Both, molten MB act as nucleating agent enhancing the crystallization rate of PP and the solidified PP act as nucleating agent to enhance the crystallization of MB. The values of half-time of crystallization ( t) and the parameter Z, from Avrami's method which characterize the kinetics of non-isothermal crystallization, showed that the crystallization rate, at the same cooling rate, decreased with the fibres and increased with the PP*; showing the retarding and accelerating effects, respectively. Some models, such as the Liu-Mo and Avrami, were found to provide a fairly satisfactory description of the crystallization kinetics of the studied blends. These results are further supported by the effective activation energy calculations by iso-conversional method of Friedman. [ABSTRACT FROM AUTHOR]

Electromagnetic shielding is one the key factors for electronic devices in their use and transportation. Polylactide (PLA) is a biodegradable polymer with a moderate biodegradability and decent mechanical properties. Replacement of traditional materials by biodegradable polymers brings about the fossil resources savings and helps solving problems related to the plastic packaging waste. In this work composites of PLA with carbon black and carbon nanofibers were described. Improvement of the material mass/electromagnetic interference SE (shielding effectiveness) ratio can be obtained by introducing foaming technology into the material preparation process. Microporous structure can greatly improve material properties such as thermal isolation, mechanical properties and in case of composites filled with carbonaceous fillers such as carbon black carbon fibres – also the electrical conductivity. In order to improve their application range and reduce density, a cellular structure was created using chemical blowing agent. It was found that in low loaded composites (although above the percolation level) the shielding effectiveness relies on the amount of a conductive filler but it may be additionally enhanced by the foaming process. Electrical properties, electromagnetic shielding effectiveness and morphology of cellular composites for described polymer-filler systems have been presented. [ABSTRACT FROM AUTHOR]

Biodegradable polymer nanocomposites of poly(lactic acid) and nanoclay (Cloisite 30B) samples were prepared with compositions of 0%, 1%, 2%, 3%, 4%, and 5% (by mass) nanoclay using extrusion followed by injection molding. An exfoliated morphology was observed using x-ray diffraction. The nanocomposites were investigated for their mechanical properties using dynamic mechanical analysis (DMA) and tensile testing. The combination with 3% nanoclay was found to be optimum as a result of having the greatest mechanical strength. The fracture surfaces of the samples were also observed with the help of a scanning electron microscopy, and the images obtained complied with the experimental values attained for the samples, indicating more ductile fractures for those samples with greater mechanical strength. The thermal properties of the composites were studied with the help of differential scanning calorimetry and DMA data, and it was found that the trend followed by the glass transition temperature values obtained by both the methods was the same. [ABSTRACT FROM PUBLISHER]

The aim of the present study was to verify that a whey protein-based layer can improve oxygen barrier properties of commercial compostable plastic film, while not hindering the biodegradability of the compostable film as well as not affecting the quality of the compost. The whey protein-based coating was applied on a biodegradable commercial film certified to meet the requirements of EN13432. Oxygen barrier properties were significantly improved by the presence of the whey protein layer. This result is particularly important since biodegradable packaging generally lack in maintaining barrier properties and the use of not degradable materials to improve barrier to gas and water vapour compromises the composting of the final packaging. In addition to that, it was important to assess the biodegradability of the whey protein layer itself since natural polymers may became not degradable if cross-linked or blended with not degradable additives. The material based on denatured whey protein and plasticizer presented fast biodegradability even after application on the commercial film. These positive results have potential to be used in new cost effective and ecological food packaging designs. [ABSTRACT FROM AUTHOR]

Highlights: [•] We prepared the TPCS/LDPE composites modified by carrageenan and/or cotton fibers. [•] The IR O–H stretching peak of the modified composites shifts to lower wavenumber. [•] Stress and Young’s modulus of the modified composites increase significantly. [•] The modified composites degrade faster than the non-modified composite. [Copyright &y& Elsevier]

This study aimed to prepare novel biodegradable polymeric composites based on poly(3-allyloxy-1,2-propylene) succinate (PSAGE). These composite materials are composed of poly(ester-anhydride) (PEA) microspheres embedded in polyester matrix prepared by crosslinking PSAGE with oligo(1,2-propylene maleate) and methacrylic monomers. Methyl methacrylate and one of hydrophilic oligo(ethylene glycol) dimethacrytes with different length of oligooxyethylene chains were used as polymerizable solvents. Incorporation of microspheres that degrade faster than crosslinked polyester matrices enables formation of porous structure. The obtained materials are liquid before curing and harden in several minutes with moderate exothermic effect. The effect of the composition of polyester matrices and kind of PEA microspheres used on selected properties, such as water sorption, mechanical strength, porosity, and hydrolytic degradation behavior, was investigated. The morphology of the cured composite materials subjected to hydrolytic degradation was evaluated by SEM. [ABSTRACT FROM AUTHOR]

Abstract: A biodegradable polyethyleneoxide–polycaprolactone–polyethyleneoxide (PEO–PCL–PEO or PECE) triblock polymer was synthesized as a structure-directing agent for high-surface area silica formation. Systematic end-group functionalization of the triblock polymer, prior to its use as a structure-directing agent for high-surface area silica growth, imparts an additional reactive function that is exploited to grow a continuous organic phase within and around the silica particles. Hence, the biodegradable triblock also acts as a macromer whose dual function leads to in-situ generation of intimately mixed biopolymer/nanoporous–silica composite networks. This composite can be both biodegradable and biocompatible, and the modulus is comparable to other non-biodegradable materials. [Copyright &y& Elsevier]

Wood fibers are easily available as a waste material, and their incorporation into polymeric matrices results in a reduction of the cost of composite products. On the other hand, poly(3-hydroxybutyrate-co-3-hydroxyvalerate) is a biodegradable bacterial polyester and it is a potential candidate to replace conventional polymers in composites. The aim of this work was to evaluate the percentage of wood fiber to be incorporated in the poly(3-hydroxybutyrate-co-3-hydroxyvalerate) matrix and to investigate the effect of Struktol® as a processing aid on the final properties of biocomposites. Therefore, biocomposites of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) were processed with addition of 0–40 wt% of wood powder with and without Struktol®. Mechanical properties, morphology, water absorption, and thermal stability were determined. The presence of Struktol® improved 104% the tensile modulus of the biocomposites when compared to the neat poly(3-hydroxybutyrate-co-3-hydroxyvalerate), reduced the water absorption for biocomposites up to 20 wt% of wood powder, and reduced the thermal stability. The biocomposites with 10 wt% of wood powder are the one with the best properties in relation to the others, independently of the presence of Struktol®. [ABSTRACT FROM PUBLISHER]

Abstract: Polymer composites were fabricated with poly(lactic acid) (PLA) and cellulosic natural fibers combining the wet-laid fiber sheet forming method with the film stacking composite-making process. The natural fibers studied included hardwood high yield pulp, softwood high yield pulp, and bleached kraft softwood pulp fibers. Composite mechanical and thermal properties were characterized. The incorporation of pulp fibers significantly increased the composite storage moduli and elasticity, promoted the cold crystallization and recrystallization of PLA, and dramatically improved composite tensile moduli and strengths. The highest composite tensile strength achieved was 121MPa, nearly one fold higher than that of the neat PLA. The overall fiber efficiency factors for composite tensile strengths derived from the micromechanics models were found to be much higher than that of conventional random short fiber-reinforced composites, suggesting the fiber–fiber bond also positively contributed to the composites’ strengths. [Copyright &y& Elsevier]

Abstract: Recently, owing to the increasing energy consumption and environment pollution problems, a fundamental understanding of thermo-regulating biodegradable polymer composites is becoming very significant. In this work, a smart biodegradable polymer composite based on microencapsulated phase change materials (MicroPCMs) and poly(3-hydroxybutyrate-co-4-hydroxybutyrate) (P3HB4HB) was fabricated. FE-SEM images revealed that there exists a good interfacial adhesion between the polymer and MicroPCMs. The thermal properties and dynamic mechanical behaviors were examined using DSC, TGA and DMA, respectively. The results indicated that the higher the MicroPCMs content, the higher is the heat storage ability of the composite. The incorporation of MicroPCMs has evidently improved the thermal stability of the composite but decreased its storage modulus. When the loading content of MicroPCMs in the composite is beyond 10% by weight, only a very slight descending tendency of glass transition temperature (T g) was found. [Copyright &y& Elsevier]

With increasing environmental awareness and ecological risk, green composites have gained more and more research attention, as they have the potential to be attractive than the traditional petroleum-based composites which are toxic and nonbiodegradable. Because of their lightweight, friendly processing and acoustic insulation, green composites have been used widely ranging from aerospace sector to household applications. The end-of-life concern with many polymeric composites has also limited their application spectrum. The green composites not only replace the traditional materials such as steel and wood but also challenge certain nonbiodegradable polymer composites. The present research initiative aims at highlighting the issues and challenges in the development and characterization of poly lactic acid–based green composites. A few of these important composites and their mechanical properties (tensile, compressive, flexural, and impact strength) have been reported in this study. The focus is the identification of the possible areas for their novel applications. A study has been conducted to categorize the various types of green composites on the basis of their physical, chemical, and mechanical characteristics. [ABSTRACT FROM PUBLISHER]

Abstract: Plastics are a major constituent of municipal solid waste that pose a growing disposal and environmental pollution problem due to their recalcitrant nature. To reduce their environmental impacts and allow them to be transformed during organic waste recycling processes, various materials have recently been introduced to improve the biodegradability of plastics. These include conventional plastics amended with additives that are meant to enhance their biodegradability, bio-based plastics and natural fiber composites. In this study, the rate and extent of mineralization of a wide range of commercially available plastic alternative materials were determined during composting, anaerobic digestion and soil incubation. The biodegradability was assessed by measuring the amount of carbon mineralized from these materials during incubation under conditions that simulate these three environments and by examination of the materials by scanning electron micrography (SEM). The results showed that during a 660 day soil incubation, substantial mineralization was observed for polyhydroxyalkanoate plastics, starch-based plastics and for materials made from compost. However, only a polyhydroxyalkanoate-based plastic biodegraded at a rate similar to the positive control (cellulose). No significant degradation was observed for polyethylene or polypropylene plastics or the same plastics amended with commercial additives meant to confer biodegradability. During anaerobic digestion for 50 days, 20–25% of the bio-based materials but less than 2% of the additive containing plastics were converted to biogas (CH4 + CO2). After 115 days of composting, 0.6% of an additive amended polypropylene, 50% of a plastarch material and 12% of a soy wax permeated paper pulp was converted to carbon dioxide. SEM analysis showed substantial disintegration of polyhydroxyalkanoate-based plastic, some surface changes for other bio-based plastics and coconut coir materials but no evidence of degradation of polypropylene or polypropylene containing additives. Although certain bio-based plastics and natural fibers biodegraded to an appreciable extent in the three environments, only a polyhydroxyalkanoate-based resin biodegraded to significant extents during the time scale of composting and anaerobic digestion processes used for solid waste management. [Copyright &y& Elsevier]

Biodegradable poly(butylene carbonate)/fumed silica (PBC/SiO) nanocomposites were prepared by melt compounding. The PBC/SiO nanocomposites exhibited a good dispersion of aggregates of SiO in the PBC matrix, and an improvement in mechanical properties. Nanoparticles affect, also, the thermal properties of PBC and especially the crystallization rate, which in all nanocomposites is faster than that of pure PBC. Due to ongoing crystallization and the crystal perfection during heating process, the melting peak of PBC shifted to higher temperature when heating from amorphous state with decreasing heating rate. With increasing cooling rate, the non-isothermal crystallization exotherms became wider and shifted to lower temperature. At a given cooling rate, the crystallization peak temperature of neat PBC was lower than that of its nanocomposite. Non-isothermal crystallization kinetic procedure, the method of Ozawa, was applied to the first deconvoluted DSC peak only by processing the data related to DSC peak. The average value of Ozawa exponent m of pure PBC is 3.04, while the one of its nanocomposite is about 2.98. Moreover, the thermal stability of the nanocomposites was increased. The T enhancement of the nanocomposite was remarkable. [ABSTRACT FROM AUTHOR]

Partially biodegradable green composites have been made by incorporating vakka fibers as reinforcement in the polyester matrix. The influence of fiber content and temperature on thermal conductivity, specific heat and thermal diffusivity of composites was investigated. The transverse thermal conductivity of unidirectional composites was investigated experimentally by a guarded heat flow meter method. It was observed that the thermal conductivity of composite decreased with increase in fiber content and at maximum volume fraction of fiber, thermal conductivity of the composites was found to be 0.179 W/m · K. Moreover, the experimental results of thermal conductivity as a function of volume fraction were compared with theoretical model. Thermal conductivity and specific heat capacity of the composite increased with temperature. The lowest thermal diffusivity of 0.55 × 10−7 m2/s for the composite was achieved at a temperature of 120℃. Fire behavior of vakka fiber composite and virgin polyester was investigated using cone calorimeter. The composite ignite earlier and emit lower values of heat release rate and peak heat release rate, when compared to neat polyester resin. Theoretical models were used to predict time to flashover and ignition temperature using cone calorimeter test results as input data. [ABSTRACT FROM AUTHOR]

Abstract: In this study, composites of semicrystalline, biodegradable polylactide (PLA) and poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHB-HHx) were prepared by direct melt compounding. The physical and thermal properties of the composites were investigated as a function of the composition ratio. Differential scanning calorimetry analysis indicated that PLA and PHB-HHx formed immiscible composites over the observed range of composition. The crystallization of PLA was gradually suppressed by increasing proportions of PHB-HHx. Dynamic mechanical analysis results confirmed that the innate ductility of PHB-HHX and its inhibiting effect on PLA crystallization improved the stiffness of the composite compared to those of neat PLA. The infrared spectra of the immiscible PLA/PHB-HHx composites at two crystallization temperatures (30°C, 130°C) were obtained and presented. At 30°C, PHB-HHx existed as crystalline domains in the PLA matrix, while, amorphous phase of molten PHB-HHx was diffused within the crystalline phase of PLA at 130°C. The interaction between PHB-HHX and PLA could not be elucidated from the temperature data. Mechanical tests showed that the addition of PHB-HHx improves ductility of PLA/PHB-HHx composite. Morphological analysis revealed that small proportions of PHB-HHx exhibited less tendency to aggregate, which resulted in greater plastic deformation and improved toughness. From this study, PLA blended with small portions of PHB-HHx may further expand the use of bio-friendly resources in a variety of applications such as flexible films, food packaging and something like that. [Copyright &y& Elsevier]

Abstract: The applications of natural fibre/polymer composites in civil engineering are mostly concentrated on non-load bearing indoor components due to its vulnerability to environmental attack. This paper evaluates the characteristics of several natural fibre composites exposed to moisture, thermal, fire, and ultraviolet degradation through an extensive literature review. The effects of chemical additives such as fibre treatments, fire retardants and Ultraviolet (UV) stabilizers are also addressed. Based on the evaluation conducted, optimum fibre content provides strength in a polymer composite but it also becomes an entry point for moisture attack. Several fibre treatments are also being used to improve fibre/matrix interface, thereby increasing moisture durability. However, the treated fibres were found to behave poorly when exposed to weather. The addition of UV stabilizers and fire retardants are suggested to enhance outdoor and fire performance of natural fibre/polymer composite but compromises its strength. Therefore, from the collected data and various experimental results, it was concluded that an optimum blend ratio of chemical additives must be employed to achieve a balance between strength and durability requirements for natural fibre composites. [Copyright &y& Elsevier]

Short jute fiber reinforced polypropylene (PP)-based partially biodegradable composites (5–30 wt.% fiber) were prepared by extrusion followed by compression molding process. Short jute fibers acted as potential reinforcing agents for PP matrix. Tensile strength, bending strength, tensile modulus, bending modulus, and elongation at break of the composites (20% jute) were found to be 27 MPa, 36 MPa, 0.74 GPa, 2.4 GPa, and 78%, respectively. The prepared composites (20% fiber) were exposed to gamma radiation (2.5–10 kGy). The irradiated (5 kGy) composites (20% jute) gained significantly higher strength and modulus than un-irradiated composites. Six months soil degradation tests revealed that irradiated composites retained much of its mechanical properties than their control counterpart composites. A reaction mechanism was proposed between jute and PP due to irradiation treatment. Surface and interface morphologies of the composites were characterized by scanning electron microscopy. [ABSTRACT FROM PUBLISHER]

Abstract: The effect of UV-C irradiation of the TPS and PCL biocomposites with sisal bleached fibers was investigated. The biocomposite was UV-C irradiated at room temperature under air atmosphere. The structural and morphological changes produced when the films were exposed to UV irradiation for 142 h, were monitored using Scanning Electron Microscopy (SEM), Mechanical Tensile Tests, Differential Scanning Calorimetry (DSC), X-ray diffraction, Thermogravimetric analysis (TGA), and Fourier transform infra-red analysis (FTIR). Addition of 5–10% fibers in composites exhibited improved mechanical and thermal properties attributed to more efficient dispersibility of fiber in the matrix and good compatibility between fibers and the matrix polymer, however, after irradiated, the tensile properties decreased due to chain scission. The samples of irradiated PCL and TPS showed crystallinity increase, whereas the blend and composites showed a decrease in crystallinity. The DSC and X-ray diffraction studies suggested interaction between polymers in the blend via carboxyl groups in thermoplastic starch-PCL and hydroxyl groups in fibers. [Copyright &y& Elsevier]