Biodegradable Polymer Composites Research Articles

Study of dielectric properties of electron beam irradiated luffa fiber/PLA composites

The complex dielectric relaxation behavior of a biodegradable polymer composite is probed in the present investigation. The polymer composite was modeled using biodegradable polymer poly (lactic) acid (PLA) as matrix and natural fiber of Luffa cylindrica (LC) as reinforcement using microcompounding and injection molding. Aforetime the LC fibers used as reinforcement in PLA matrix, the LC fibers were exposed to 6 MeV electron beam of varying doses from 0.5 to 10.0 Gy generated from medical LINAC at room temperature 26°C in presence of air. The modification in dielectric properties such as dielectric constant, dielectric loss factor, and ac conductivity was investigated in frequency range from 100 Hz to 1 MHz. The dielectric constant of virgin PLA increased from 61 to a maximum of 94 recording 52%increase when the electron beam-irradiated LC fiber is used as reinforcement in PLA matrix. The variation of dielectric constant and the dielectric loss factor in the frequency domain adhere to Debye model. However resonance peaks detected in the frequency spectrum of dielectric loss factor with the Cole-Cole variation substantiate the presence of multiple relaxations in the dielectric spectrum.

Mechanical, thermal and hydrodegradation behavior of poly (3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) composites with agricultural fibers as reinforcing fillers

Fully biodegradable polymer composites based on the bacterial polyester, poly (3-hydroxybutyrate-co-3-hydroxyvalerate), (PHBV), were produced using injection molding. Agricultural reinforcements in the form of nettle fibers (stalks and leaves), pine cones flour, and walnut shells flour were used in the amount of 15 wt%. The impact of natural additives on mechanical properties (tensile, flexural, and impact) at three different temperatures (−24, 23, and 80 °C) has been studied. For all the tested composites, Young's modulus was improved by ~20% with a slight decrease in the tensile strength. The mechanical properties correspond well with the DSC results. The values of the degree of crystallinity for the composites are higher or equal to those for neat PHBV, only the composites with stalk nettle fibers were characterized by a reduced degree of crystallinity. Research has shown that composites have higher stiffness stability at elevated temperatures.Furthermore, the materials were subjected to hydrolytic degradation at 38 °C to determine the synergistic effect between water uptake and water temperature on tensile and flexural properties. The work reveals that the addition of natural fillers increases the possibility of water absorption and decreases the value of the tested properties by ~40% after two weeks of water incubation.Recent work has shown that it is possible to produce fully biodegradable polymer composites using agricultural wastes. The addition of fibers not only reduces the price of materials but increases the stiffness of the polymer whilst controlling the biodegradation process. Moreover, in this approach, waste materials will be able to act as an efficient filler, what will lead to their effective management.

Green composites from natural fibers and biopolymers: A review on processing, properties, and applications

At present, environmental sustainability is a big concern due to the limited resources and the adverse impacts of petroleum-based materials. Green composites (GCs) attracted intensive research interest for the last few decades from academicians, scientists, researchers, and practitioners both from the ecological and economic point of view and are presently being considered as one of the most promising research domains. Composites produced from renewable and/or natural resources thanks to their biodegradability and sustainability properties are envisaged as the next-generation materials to meet the growing demand worldwide. GCs are intensively investigated due to their multifunctional properties and utilization in a wide variety of fields including automobile, marine, aerospace, structural and infrastructural applications, packaging, electronics industry, sports, and biomedical applications. They also show potentials to replace the expensive as well as non-degradable petroleum-based composites. After the shelf life, it can be disposed of easily without harming the environment. The processing techniques, properties, and applications of green composites are comprehensively assessed in this review article. The feasibility of the naturally available fiber and polymers for green composites are also discussed highlighting the existing challenges with possible suggestions. It was intended to present a full overview of biodegradable polymer composites reinforced with natural fiber, as well as the necessary future directions for the concerned researchers.

A Review on Natural Fibre-Reinforced Biopolymer Composites: Properties and Applications

In ongoing decades, material researchers and scientists are giving more consideration towards the improvement of biobased polymer composites as various employments of items arranged by natural fibres and petrochemical polymers prompt natural awkwardness. The goal of this review paper is to provide an intensive review and applications of the foremost appropriate commonly used biodegradable polymer composites. It is imperative to build up the completely/incompletely biodegradable polymer composites without bargaining the mechanical, physical, and thermal properties which are required for the end-use applications. This reality roused to create biocomposite with better execution alongside the least natural effect. The utilization of natural fibre-reinforced polymer composites is concerned with the mechanical properties that are highly dependent on the morphology, hydrophilic tendency, aspect ratio, and dimensional stability of the natural fibre. With this in-depth consideration of eco-friendly biocomposites, structural application materials in the infrastructure, automotive industry, and consumer applications of the following decade are attainable within the near future.

Effect of thermal annealing and filler ball-milling on the properties of highly filled polylactic acid/pecan nutshell biocomposites

Biodegradable polymer composites reinforced with agri-food lignocellulosic biowaste represent cost-effective and sustainable materials potentially able to replace traditional composites for structural, household, and packaging applications. Herein, the preparation of polylactic acid (PLA)/pecan (Carya illinoinensis) nutshell (PNS) biocomposites at high filler loading (50 wt%) is reported, alongside the effect of two environmentally friendly physical treatments, namely ball-milling of the filler and thermal annealing on biocomposites.PNS enhanced the thermal stability, the viscoelastic response, and the crystallinity of the polymer. Furthermore, filler ball-milling also increased the melt fluidity of the biocomposites, potentially improving melt processing. Finally, the presence of PNS remarkably enhanced the effect of thermal annealing in the compounds. In particular, heat deflection temperature of the biocomposites dramatically increased, up to 60 °C with respect to the non-annealed samples. Overall, these results emphasize the potential of combining natural fillers and environmentally benign physical treatments to tailor the properties of PLA biocomposites, especially for those applications which require a stiff and lightweight material with low deformability.

Biodegradable polymer composite based on NBR rubber and protein waste

The aim of this work is to characterize a biodegradable polymer composite based on butadiene-co-acrylonitrile rubber (NBR) and protein waste (ground leather). The biodegradable polymer composite was obtained by the mixing technique on a Brabender Plasti-Corder mixer and then on an electric roller (without heating), between its rollers, with sulfur vulcanization activators and Th accelerator, relative to 100 parts plasticized elastomer, obtaining 3-4 mm thick sheets, with strict observance of the technological recipe, but also of the established mode of operation. The obtained mixtures are then subjected to rheological characterization to determine the vulcanization time using the Monsanto rheometer (to determine the optimum temperature and vulcanization times in the laboratory electric press in specific molds for obtaining specimens to be subjected to subsequent characterization). Biodegradable polymeric composites based on butadiene-co-acrylonitrile rubber (NBR) and protein waste (leather waste from the footwear and leather goods industry) were made at optimal working parameters, and the characterization was performed on equipment specific to elastomers and according to standards in force for the footwear and consumer goods industry such as: plates for general purpose footwear soles as well as for water and mud environments, but also for the food industry, car mats, gaskets and components used under normal working conditions, technical plates, insoles, etc.

Strong Interface via Weak Interactions: Ultratough and Malleable Polylactic acid/Polyhydroxybutyrate Biocomposites.

Bio-based and biodegradable polymer composites, most notably poly(l-lactic acid) (PLLA) and poly(3-hydroxybutyrate) (PHB), represent a promising solution to replace conventional petroleum-based plastics. However, the brittleness and low miscibility of PLLA and PHB remain two major obstacles to practical applications. In this work, first PLLA/PHB blends are reported by melt mixing with a rigid component, poly(methyl methacrylate) (PMMA). Driven by favorable entropy, PMMA forms an interfacial nanolayer, which transforms the morphology of resultant blends. The ternary blends show 55-fold increase in elongation, 50-fold in toughness, and metal-like malleability (≈180° bending and twisting), while retaining its high stiffness (3.4GPa) and strength (≈50MPa). The mechanical improvement arises from numerous craze fibrils and shear deformation of the matrix, induced by the incorporated PMMA. Furthermore, this generic strategy can be applied to design other mechanically robust biocomposites for advanced green devices.

Crystallization Behaviors of Composites Comprising Biodegradable Polyester and Functional Nucleation Agent

In this study, a thorough study of the crystallization behaviors of the biodegradable polymer composites of poly(ethylene succinate) (PESu) and hexagonal boron nitride (h-BN) was carried out. We found that h-BN had a significant nucleation effect on crystallization behaviors. DSC isothermal crystallization results demonstrated that the crystallization time of the PESu/h-BN composites became shorter after adding h-BN. The rate constant k values calculated from the Avrami equation were larger for the composites, demonstrating that PESu’s crystallization rate was increased by adding h-BN. TEM and SEM images showed the well-dispersed h-BN in the PESu matrix. Optical microscopy revealed that the PESu/h-BN composites formed more and smaller spherulites than neat PESu did, which confirmed that h-BN caused the nucleation effect. H-BN also accelerated non-isothermal crystallization kinetics. We discussed the behaviors of the Mo model, which demonstrated that h-BN promoted the kinetics of non-isothermal crystallization. The XRD diffraction patterns showed that h-BN in the composites would not obviously change the crystalline structure of PESu.

Intumescent-Grafted Bamboo Charcoal: A Natural Nontoxic Fire-Retardant Filler for Polylactic Acid (PLA) Composites.

In this work, an alternative flame-retardant filler based on phosphate- and urea-grafted bamboo charcoal (BC-m) at 10–30 wt % addition was aimed at improving the flame retardancy of polylactic acid (PLA) composites. The filler caused only a small reduction in strength properties but a slight increase in the modulus of elasticity of PLA composites. BC-m significantly improved the flame-retardant performance compared with pure BC. The limiting oxygen index (LOI) was 28.0 vol % when 10 wt % of BC-m was added, and 32.1 vol % for 30 wt % addition, which was much greater than the value of 22.5 vol % for 30 wt % pure BC. Unlike pure BC, adding BC-m at 20 wt % or more gave a UL-94 vertical flame test rating of V-0 with significantly reduced melt dripping. The peak heat release rate (pHRR) and total heat release (THR) of BC-m/PLA composites decreased by more than 50% compared with pure PLA, and the values for 20% BC-m were significantly less than that for 25% BC addition. The grafted biochar-based system provides an effective flame retardancy effect by a condensed-phase protective barrier through the rapid formation of a dense, honeycomb-like cross-linked carbonized char layer. The results suggest a promising route to enhancing the flame-retardant properties of biodegradable polymer composites using nontoxic, more environmentally friendly grafted biochar.

A review on the processing–morphology–property relationship in biodegradable polymer composites containing carbon nanotubes and nanofibers

AbstractCarbon nanofillers containing biodegradable polymer composites have become an emerging frontier in materials science and engineering because of their potential as environmentally friendly materials in multiple applications, from load‐bearing to advanced packaging to biomedical applications. Herein, we present the effect of processing parameters on the final morphology and the resulting properties of the biodegradable polymer composites containing carbon nanotubes (CNTs) or carbon nanofibers (CNFs). Various strategies can be employed to develop such composites; however, the type of morphology, which results during processing, significantly affects the final properties of the obtained composites. Therefore, various processing strategies such as melt‐blending, additive manufacturing, and electrospinning are critically reviewed, together with the potential applications in load‐bearing, tissue engineering, electromagnetic shielding, gas sensing, and packaging. Finally, we discuss the existing challenges and future directions in designing CNTs/CNFs containing biodegradable polymer composites with desired properties.

Thermal Behavior of the Porous Polymer Composites Based on LDPE and Natural Fillers Studied by Real Time Thermal Microscopy

Foaming of the biodegradable polymer composites and melting of the gas-filled materials were studied using thermal microscopy. Composite materials under investigation were based on the low density polyethylene and natural products used as the polymer composite fillers: wood flour and corn starch. Porous structure of the composite material was obtained using a chemical porogen “Hydrocerol BIF”. It has been shown that the foaming and melting processes occur differently in the polymer composite samples containing either different amount of the fillers or the same content of the filler with different particle size fractions. Thermal behavior of the composite samples was shown to be different from the behavior of pure polyethylene, which indicates non-additivity (superadditivity) of the contribution of the above components to the thermal behavior of the final composite material. All the results obtained using heating stage (hot stage) microscopy were in good agreement with the SEM and DSC data.

Reactive TiO2 Nanoparticles Compatibilized PLLA/PBSU Blends: Fully Biodegradable Polymer Composites with Improved Physical, Antibacterial and Degradable Properties

Reactive TiO2 Nanoparticles Compatibilized PLLA/PBSU Blends: Fully Biodegradable Polymer Composites with Improved Physical, Antibacterial and Degradable Properties

Melt behavior of polypropylene‐co‐ethylene composites filled with dual component of sago and kenaf natural filler

AbstractA dual component natural filler system featuring discrete function appears to be suitable for modulating smooth flow of pseudo‐plastic into formulated biodegradable polymer composite. Polypropylene‐co‐ethylene (PPcoE) filled with sago starch and different kenaf powder loadings were compounded using co‐rotating twin‐screw extruder to produce dual component polymer composite. The flow characteristics of the composites were measured using capillary rheometer and Bagley corrections were performed to achieve the true rheological data. In addition, data collected from the twin‐screw extruder were used to calculate the composite apparent rheological value. The flow properties of PPcoE filled with sago starch (PPcoE/sago) exhibited deviation from the common non‐Newtonian thermoplastic flow paths at high shear rates. Interestingly, the addition of kenaf powder into the PPcoE/sago starch blend stabilized the melted composite flow stream. The calculation of interfacial tension revealed that the flow corrections were related to the phase selective localization of kenaf particle, which preferably embedded between the sago particles rather than in the surrounding PPcoE phase thus reducing the effect of sago clustering. At higher extrusion temperature, the extruded composite indicated sign of flow instability due to factors of high amount of kenaf powder loading and the degradation of sago starch and PPcoE chains.

Preparation and Evaluation of Biodegradation Performance of Potato Starch Mixed LDPE Polymer Composites

The potential of biodegradable polymers has long been appreciated. In this work, an attempt has been made to synthesize biodegradable polymer composite from potato starch and low density polyethylene (LDPE) with different ratios of starch (0%-15% w/w) by using an extruder. The structure and morphology of film surfaces was studied using X-ray diffraction and scanning electron microscopy (SEM) respectively. The physical (density, water absorption), mechanical (tensile, flexural) and thermal (TGA and DTA) analyses of starch/LDPE bio-composites were evaluated through standard methods and instruments. Biodegradation tendency was investigated utilizing soil burial and Rockwell micro-hardness test.The results revealed that the density and water absorption of polymer blends increased with increasing the starch content in starch/LDPE composites. The tensile strength and elongation at break decreased with starch content whereas the elastic modulus, flexural strength and flexural modulus rose. The biodegradability of composites enhanced by increasing the starch content and the result was backed by weight loss during burial of the samples in soil for 90 days. Microhardness test also supported the biodegradation probability as hardness found to reduce extensively after soil burial. However, further study to decide the optimum starch loading alongwith some modifications to starch and LDPE is highly suggested to have a biodegradable LDPE polymer composite in a realistic time frame.

Critical Review of Biodegradable and Bioactive Polymer Composites for Bone Tissue Engineering and Drug Delivery Applications.

In the determination of the bioavailability of drugs administered orally, the drugs’ solubility and permeability play a crucial role. For absorption of drug molecules and production of a pharmacological response, solubility is an important parameter that defines the concentration of the drug in systemic circulation. It is a challenging task to improve the oral bioavailability of drugs that have poor water solubility. Most drug molecules are either poorly soluble or insoluble in aqueous environments. Polymer nanocomposites are combinations of two or more different materials that possess unique characteristics and are fused together with sufficient energy in such a manner that the resultant material will have the best properties of both materials. These polymeric materials (biodegradable and other naturally bioactive polymers) are comprised of nanosized particles in a composition of other materials. A systematic search was carried out on Web of Science and SCOPUS using different keywords, and 485 records were found. After the screening and eligibility process, 88 journal articles were found to be eligible, and hence selected to be reviewed and analyzed. Biocompatible and biodegradable materials have emerged in the manufacture of therapeutic and pharmacologic devices, such as impermanent implantation and 3D scaffolds for tissue regeneration and biomedical applications. Substantial effort has been made in the usage of bio-based polymers for potential pharmacologic and biomedical purposes, including targeted deliveries and drug carriers for regulated drug release. These implementations necessitate unique physicochemical and pharmacokinetic, microbiological, metabolic, and degradation characteristics of the materials in order to provide prolific therapeutic treatments. As a result, a broadly diverse spectrum of natural or artificially synthesized polymers capable of enzymatic hydrolysis, hydrolyzing, or enzyme decomposition are being explored for biomedical purposes. This summary examines the contemporary status of biodegradable naturally and synthetically derived polymers for biomedical fields, such as tissue engineering, regenerative medicine, bioengineering, targeted drug discovery and delivery, implantation, and wound repair and healing. This review presents an insight into a number of the commonly used tissue engineering applications, including drug delivery carrier systems, demonstrated in the recent findings. Due to the inherent remarkable properties of biodegradable and bioactive polymers, such as their antimicrobial, antitumor, anti-inflammatory, and anticancer activities, certain materials have gained significant interest in recent years. These systems are also actively being researched to improve therapeutic activity and mitigate adverse consequences. In this article, we also present the main drug delivery systems reported in the literature and the main methods available to impregnate the polymeric scaffolds with drugs, their properties, and their respective benefits for tissue engineering.

A Brief Review on the Influence of Ionic Liquids on the Mechanical, Thermal, and Chemical Properties of Biodegradable Polymer Composites.

Biodegradable polymers are an exceptional class of polymers that can be decomposed by bacteria. They have received significant interest from researchers in several fields. Besides this, biodegradable polymers can also be incorporated with fillers to fabricate biodegradable polymer composites. Recently, a variety of ionic liquids have also been applied in the fabrication of the polymer composites. In this brief review, two types of fillers that are utilized for the fabrication of biodegradable polymer composites, specifically organic fillers and inorganic fillers, are described. Three types of synthetic biodegradable polymers that are commonly used in biodegradable polymer composites, namely polylactic acid (PLA), polybutylene succinate (PBS), and polycaprolactone (PCL), are reviewed as well. Additionally, the influence of two types of ionic liquid, namely alkylimidazolium- and alkylphosphonium-based ionic liquids, on the mechanical, thermal, and chemical properties of the polymer composites, is also briefly reviewed. This review may be beneficial in providing insights into polymer composite investigators by enhancing the properties of biodegradable polymer composites via the employment of ionic liquids.

​Coconut Shell Powder Reinforced Epoxy Composites: A Review

Fibers are of two type’s natural fiber and synthetic fiber. Natural fibers include those made from plant and animal sources. The natural fiber composites can be very cost effective material and have turned out to be an alternative solution to the ever depleting petroleum sources and have reduced the nuisance of pollution. The production of complete natural fiber based materials as a substitute for petroleum-based products would not be an economical solution. A more viable solution would be to combine petroleum and bio-based resources to develop a cost-effective product with diverse applications. The application of natural fiber-reinforced composites has been extended to almost all fields such as building and construction industry, storage devices (post-boxes, grain storage silos, bio-gas containers etc.), furniture and electrical devices. Coconut shell is a lignocellulosic agro waste which is burnt or left to decay in environment. These can be a very interesting material as filler in biodegradable polymer composites, due to its good thermal stability compared to other agricultural waste. In context to this, review was carried out to assess the coconut shell powder reinforced epoxy composites and their mechanical, structural and thermal properties.

PH and light-responsive polycaprolactone/curcumin@zif-8 composite films with enhanced antibacterial activity.

Food packaging materials, especially biodegradable polymer composites incorporated with natural antimicrobial agents with excellent antibacterial activities, are in high demand and attracted immense attention. Herein, a polycaprolactone/curcumin@zeolitic imidazolate framework-8 (PCL/Cur@ZIF-8) composite film with enhanced antibacterial activity was developed. Curcumin, a natural photosensitizer, was loaded in the highly porous nanocrystals ZIF-8 to improve its poor water solubility and stability. The integral structure of Cur@ZIF-8 was maintained well in the PCL matrix even at the highest loading of 35% (w/w), and all composite films had good light transmittance at 420-430nm. The PCL/Cur@ZIF-8 composite films responded to the acidic growth environment of bacteria by releasing zinc ions and curcumin molecules. Furthermore, upon blue light irradiation (420-430nm, 2.2mW/cm2 ), curcumin molecules generated singlet oxygen. With the synergistic effects of zinc ions and singlet oxygen, the composite films exhibited a 99.9% reduction of Escherichia coli and Staphylococcus aureus strains when the amount of Cur@ZIF-8 loading was more than 15% (w/w), as well as a strong anti-adhesion effect on bacteria. Moreover, bacterial resuscitation tests indicated that the composite films exhibited 99.9% reduction in the adhered bacteria population through treatment with photodynamic sterilization. This is the first study presenting that the incorporated curcumin ZIF-8 nanoparticles in the matrix of polymer are pH and light responsive for anti-adhesion of bacteria, which is of great potential application as antibacterial packaging material for the food industry. PRACTICAL APPLICATION: A novel, biodegradable, pH, and light-responsive composite film was developed for antibacterial activity. Natural photosensitizer curcumin was encapsulated in ZIF-8 nanocrystals (Cur@ZIF-8) as the antimicrobial agent. With the synergistic effects of Zn2+ and singlet oxygen, the composite film exhibited a 99.9% reduction of Escherichia coli and Staphylococcus aureus strains, and a strong anti-adhesion property toward bacteria. This composite film is of great potential application as an antibacterial packaging material that enhances the shelf life of fruits, meat, and so on.

Highly rigid, fire-resistant, and sustainable polybutylene adipate terephthalate/polybutylene succinate composites reinforced with surface-treated coffee husks

Despite the increasing demand for eco-friendly polymer materials that can be employed in advanced industrial applications, the development of biodegradable polymer composites with advantageous mechanical properties and fire resistance remains a challenge. In this work, we fabricated fully biodegradable polybutylene adipate terephthalate (PBAT)/polybutylene succinate (PBS) composites reinforced with surface-treated coffee husks (CHs) with high rigidity, mechanical strength, and fire resistance. CH characterization confirmed that the surface was successfully treated with different C4 dicarboxylic acids. Morphological analysis of the composites revealed that the surface-treated CHs helped to improve both the compatibility between the matrices and the interfacial interaction between the filler and the matrices. The tensile strength and modulus of the composites increased by 96% and 278% compared to neat PBAT. Flammability and combustion tests confirmed that the combined effect of phosphorus and dicarboxylic acid surface treatment improved the fire-resistant behavior of the composites. This study thus presents a promising technique for the development of PBAT composites with suitable mechanical properties and fire resistance.

Thermoplastic starch as a component of film-forming compositions with degradable properties

A review of the literature on the production of thermoplastic starch, which is an integral part of biodegradable polymer compositions. The analysis of plasticizing additives, influence of their functional groups, chemical structure and technological parameters on physical and mechanical properties of starch compositions is carried out. The list of plasticizing additives studied should include: glycerin, water, polyethylene glycol, polypropylene glycol. Sorbitol, formamide, xylitol, dimethyl sulfoxide, gelatin, maleic anhydride, epoxidized compounds are defined as structure-forming additives. To improve the physical and mechanical properties of the starch, the addition of crosslinking agents such as citric, boric, or ascorbic acid has been proposed. According to the above review of studies, it can be stated that when creating thermoplastic starch, it is mandatory to use both plasticizing components and structure-forming, which allows the processing of thermoplastic starch by extrusion with subsequent granulation. Thermoplasticized starch due to various plasticizing additives and technological parameters of its production acquires a wide range of characteristics, which solves the problem of creating biodegradable film-forming materials. Depending on the goals, the second component of such materials may be synthetic polymers: polyethers, polycaprolactone, polyolefins, polyterephthalates, PVA and others. Technological parameters of processing in the extrusion process range from 115 °C to 190 °C in the extrusion process, which does not establish an optimized technology for thermoplastic starch and requires further research.