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Biopolymers are biodegradable and renewable and can significantly reduce environmental impacts. For this reason, biocomposites based on a plasticized starch and cross-linker matrix and with a microfibrillated OCC cardboard cellulose reinforcement were developed. Biocomposites were prepared by suspension casting with varied amounts of microfibrillated cellulose: 0, 4, 8, and 12 wt%. Polyethylene glycol diglycidyl ether (PEGDE) was used as a cross-linking, water-soluble, and non-toxic agent. Microfibrillated cellulose (MFC) from OCC cardboard showed appropriate properties and potential for good performance as a reinforcement. In general, microfiber incorporation and matrix cross-linking increased crystallization, reduced water adsorption, and improved the physical and tensile properties of the plasticized starch. Biocomposites cross-linked with PEGDE and reinforced with 12 wt% MFC showed the best properties. The chemical and structural changes induced by the cross-linking of starch chains and MFC reinforcement were confirmed by FTIR, NMR, and XRD. Biodegradation higher than 80% was achieved for most biocomposites in 15 days of laboratory compost. [ABSTRACT FROM AUTHOR]

The fiber-filled polymer composite is one of the best materials which provides a symmetrical superior strength and stiffness to structures. With the strengthening of people's environmental protection and resource reuse consciousness, the development of renewable materials, especially natural fiber-filled polymer composites, is receiving great attention. This study investigated the mechanical properties of polymer composites incorporating waste materials from the food processing industry and agricultural sources. Waste vegetal fiber-filled polymer biocomposites (WVFFPBs) with varying fiber types and 3D printing orientations were systematically fabricated. Subsequently, the tensile tests were executed to comprehensively assess the anisotropic mechanical behaviors of the WVFFPBs. The results demonstrated that WVFFPBs performed excellent anisotropic mechanical properties compared to pristine matrix samples as print orientation changed. As the printing angle increased from 0° to 90°, the tensile mechanical properties of the WVFFPBs displayed a decreasing trend. Moreover, the print orientation–anisotropic mechanical behavior relationship of 3D-printed WVFFPBs was revealed through the analysis of the material manufacturing characteristics and damage features. [ABSTRACT FROM AUTHOR]

The presented study is focused on the modification of commercially available epoxy resin with flame retardants by means of using natural substances, including quercetin hydrate and potato starch. The main aim was to obtain environmentally friendly material dedicated to rail transport that is resistant to the aging process during exploitation but also more prone to biodegradation in environmental conditions after usage. Starch is a natural biopolymer that can be applied as a pro-ecological filler, which may contribute to degradation in environmental conditions, while quercetin hydrate is able to prevent a composite from premature degradation during exploitation. To determine the aging resistance of the prepared materials, the measurements of hardness, color, mechanical properties and surface free energy were performed before and after solar aging. To assess the mechanical properties of the composite material, one-directional tensile tests were performed for three directions (0, 90, 45 degrees referred to the plate edges). Moreover, the FT-IR spectra of pristine and aged materials were obtained to observe the changes in chemical structure. Furthermore, thermogravimetric analysis was conducted to achieve information about the impact of natural substances on the thermal resistance of the achieved composites. [ABSTRACT FROM AUTHOR]

As an emerging science, tissue engineering and regenerative medicine focus on developing materials to replace, restore or improve organs or tissues and enhancing the cellular capacity to proliferate, migrate and differentiate into different cell types and specific tissues. Renewable resources have been used to develop new materials, resulting in attempts to produce various environmentally friendly biomaterials. Poly (lactic acid) (PLA) is a biopolymer known to be biodegradable and it is produced from the fermentation of carbohydrates. PLA can be combined with other polymers to produce new biomaterials with suitable physicochemical properties for tissue engineering applications. Here, the advances in modified PLA as tissue engineering materials are discussed in light of its drawbacks, such as biological inertness, low cell adhesion, and low degradation rate, and the efforts conducted to address these challenges toward the design of new enhanced alternative biomaterials. [ABSTRACT FROM AUTHOR]

The increasing concerns about plastic pollution and climate change have encouraged research into bioderived and biodegradable materials. Much attention has been focused on nanocellulose due to its abundance, biodegradability, and excellent mechanical properties. Nanocellulose-based biocomposites are a viable option to fabricate functional and sustainable materials for important engineering applications. This review addresses the most recent advances in composites, with a particular focus on biopolymer matrices such as starch, chitosan, polylactic acid, and polyvinyl alcohol. Additionally, the effects of the processing methods, the influence of additives, and the outturn of nanocellulose surface modification on the biocomposite's properties are outlined in detail. Moreover, the change in the composites' morphological, mechanical, and other physiochemical properties due to reinforcement loading is reviewed. Further, mechanical strength, thermal resistance, and the oxygen–water vapor barrier properties are enhanced with the incorporation of nanocellulose into biopolymer matrices. Furthermore, the life cycle assessment of nanocellulose and composites were considered to analyze their environmental profile. The sustainability of this alternative material is compared through different preparation routes and options. [ABSTRACT FROM AUTHOR]

This study focused on the development of a novel biocomposite material formed by a thermoplastic biodegradable polyester, poly(butylene succinate-co-adipate) (PBSA), and a carbonaceous filler as biochar (BC) derived by the pyrolysis of woody biomass waste. Composites with various BC contents (5, 10, 15, and 20 wt.%) were obtained by melt extrusion and investigated in terms of their processability, thermal, rheological, and mechanical properties. In all the composites, BC lowered melt viscosity, behaving as a lubricant, and enhancing composite extrudability and injection moulding at high temperatures up to 20 wt.% of biochar. While the use of biochar did not significantly change composite thermal stability, it increased its stiffness (Young modulus). Differential scanning calorimeter (DSC) revealed the presence of a second crystal phase induced by the filler addition. Furthermore, results suggest that biochar may form a particle network that hinders polymer chain disentanglement, reducing polymer flexibility. A biochar content of 10 wt.% was selected as the best trade-off concentration to improve the composite processability and cost competitiveness without compromising excessively the tensile properties. The findings support the use of biochar as a sustainable renewable filler and pigment for PBSA. Biochar is a suitable candidate to replace more traditional carbon black pigments for the production of biodegradable and inexpensive innovative PBSA composites with potential fertilizing properties to be used in agricultural applications. [ABSTRACT FROM AUTHOR]

The usage of new cellulosic fibers in industrial applications is massive because of its excellent performances. These fibers are utilized especially for manufacture of high-performance composites. Coconut leaf sheath (CLS) fibers are extracted for leaf sheath of coconut tree. The aim of this paper is to study the possibility of using a natural fiber CLS as an alternative for polymer composites. In the current study, the consequence of NaOH treatment on structural, thermal and morphological behavior of treated and untreated coconut leaf sheath (CLS) fiber in terms of single fiber tensile strength, Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (×RD), ther)mogravimetric analysis (TGA) and differential scanning calorimeter (DSC) has been explored. From SEM analysis, it was identified globular lumps spread consistently over the fiber which could help the mechanical interlock with the resin. The outcomes from the experimentation exposed that the NaOH treatment has impacted in the eradication of amorphous hemicellulose and lignin contents from the CLS fiber surface and in turn resulted in excellent structural and thermal stability behaviour of fiber. The present work endorses the great potential of CLS fibers to be utilized for bio-reinforcement in order to fabricate lightweight composite structures, employed in automobile and structural applications. [ABSTRACT FROM AUTHOR]

This work investigates the rheological behavior and characteristics of solutions and convened biopolymer films from Chitosan (Chi) modified by kombucha-derived bacterial cellulose (KBC). The Arrhenius equation and the Ostwald de Waele model (power-law) revealed that the Chi/KBC solutions exhibited non-Newtonian behavior. Both temperature and KBC concentration strongly affected their solution viscosity. With the selection of a proper solvent for chitosan solubilization, it may be possible to improve the performances of chitosan films for specific applications. The elasticity of the prepared films containing KBC 10% w/w was preferable when compared to the controls. FTIR analysis has confirmed the presence of bacterial cellulose, chitosan acetate, and chitosan lactate as the corresponding components in the produced biopolymer films. The thermal behaviors of the Chi (lactic acid)/KBC samples showed slightly higher stability than Chi (acetic acid)/KBC. Generally, these results will be helpful in the preparation processes of the solutions and biopolymer films of Chi dissolved in acetic or lactic acid modified by KBC powder to fabricate food packaging, scaffolds, and bioprinting inks, or products related to injection or direct extrusion through a needle. [ABSTRACT FROM AUTHOR]

Natural fibre biopolymer composites with both fibres and matrix being derived from biomaterials are increasingly used in demanding applications, such as sensing, packaging, building, and transport, and require good electrical, thermal, and flame retardant properties. Herein, an investigation of the effectiveness of functionalising nonwoven cotton/poly(lactic acid) (PLA) fibre mats with graphene oxide nanosheets has been reported by using a facile dip-coating method followed by thermal reduction for enhancing the electric, thermal, and abrasion-resistance properties. The manufacturing processes for preparing biocomposites and introducing functionality are readily scalable. Experimental results reveal that with the addition of less than 0.5 wt% graphene nanoplatelets, the biocomposites showed significant improvements in abrasion resistance, electrical conductivity, thermal conductivity, and diffusivity. Furthermore, the composite shows excellent piezo-resistivity to act as strain sensors with a gauge factor of 2.59 at strains up to 1%. [ABSTRACT FROM AUTHOR]

The use of biopolymers for tissue engineering has recently gained attention due to the need for safer and highly compatible materials. Starch is one of the most used biopolymers for membrane preparation. However, incorporating other polymers into starch membranes introduces improvements, such as better thermal and mechanical resistance and increased water affinity, as we reported in our previous work. There are few reports in the literature on the biocompatibility of starch/chicken gelatin composites. We assessed the in vivo biocompatibility of the five composites (T1–T5) cassava starch/gelatin membranes with subdermal implantations in biomodels at 30, 60, and 90 days. The FT-IR spectroscopy analysis demonstrated the main functional groups for starch and chicken gelatin. At the same time, the thermal study exhibited an increase in thermal resistance for T3 and T4, with a remaining mass (~15 wt.%) at 800 °C. The microstructure analysis for the T2–T4 demonstrated evident roughness changes with porosity presence due to starch and gelatin mixture. The decrease in the starch content in the composites also decreased the gelatinization heats for T3 and T4 (195.67, 196.40 J/g, respectively). Finally, the implantation results demonstrated that the formulations exhibited differences in the degradation and resorption capacities according to the starch content, which is easily degraded by amylases. However, the histological results showed that the samples demonstrated almost complete reabsorption without a severe immune response, indicating a high in vivo biocompatibility. These results show that the cassava starch/chicken gelatin composites are promising membrane materials for tissue engineering applications. [ABSTRACT FROM AUTHOR]

Fungal biomass (FB), a by-product of the fermentation processes produced in large volumes, is a promising biomaterial that can be incorporated into poly(lactic acid) (PLA) to develop enhanced biocomposites that fully comply with the biobased circular economy concept. The PLA/FB composites, with the addition of triethyl citrate (TEC) as a biobased plasticizer, were fabricated by a microcompounder at 150 °C followed by injection molding. The effects of FB (10 and 20 wt %) and TEC (5, 10, and 15 wt %) contents on the mechanical, thermal and surface properties of the biocomposites were analyzed by several techniques. The PLA/FB/TEC composites showed a rough surface in their fracture section. A progressive decrease in tensile strength and Young's modulus was observed with increasing FB and TEC, while elongation at break and impact strength started to increase. The neat PLA and biocomposite containing 10% FB and 15% TEC exhibited the lowest (3.84%) and highest (224%) elongation at break, respectively. For all blends containing FB, the glass transition, crystallization and melting temperatures were shifted toward lower values compared to the neat PLA. The incorporation of FB to PLA thus offers the possibility to overcome one of the main drawbacks of PLA, which is brittleness. [ABSTRACT FROM AUTHOR]

High-power laser irradiation interaction with natural polymers in biocomposites and Laser-Induced Chitin Deacetylation (LICD) was studied in this work, in order to produce thin films consisting of chitosan composite. The new method can lead to a cutting-edge technology, as a response to the concern regarding the accumulation of "natural biological waste" and its use. The process consists of high-power laser irradiation applied on oyster shells as the target and deposition of the ablated material on different substrates. The obtained thin films we analyzed by FTIR, UV-VIS and LIF spectroscopy, as well as SEM-EDS and AFM. All the results indicated that chitin was extracted from the shell composite material and converted to chitosan by deacetylation. It was, thus, evidenced that chemical transformation in the chitin polymer side-chain occurs during laser irradiation of the oyster shell and in the resulted plasma plume of ablation. The numerical simulation in COMSOL performed for this study anticipates and confirms the experimental results of chitin deacetylation, also providing information about the conditions required for the physico-chemical processes involved. The high sorption properties of the thin films obtained by a LICD procedure is evidenced in the study. This quality suggests that they should be used in transdermal patch construction due to the known hemostatic and antibacterial effects of chitosan. The resulting composite materials, consisting of the chitosan thin films deposited on hemp fabric, are also suitable for micro-filters in water decontamination or in other filtering processes. [ABSTRACT FROM AUTHOR]

This research aimed to investigate the effects of using wood leachate (WL) powder as a cost-effective filler added to novel poly (lactic acid) biocomposites and evaluate their mechanical, thermal, morphological, and antibacterial properties. Fourier transform infrared spectroscopy (FTIR), tensile test, Charpy impact test, Shore hardness, scanning electron microscope (SEM), differential scanning calorimetry (DSC), contact angle, and bacterial growth inhibition tests were employed to characterize the developed biocomposites. The SEM results indicated a proper filler dispersion in the polymer matrix. WL powder improved the hydrophobic nature in the adjusted sample's contact angle experiment. Markedly, the results showed that the addition of WL filler improved the mechanical properties of the fabricated biocomposites. The thermal analysis determined the development in crystallization behavior and a decline in glass transition temperature (Tg) from 60.1 to 49.3 °C in 7% PLA-WL biocomposites. The PLA-WL biocomposites exhibited an antibacterial activity according to the inhibition zone for Escherichia coli bacteria. The developed novel PLA-WL composites can be effectively utilized in various value-added industrial applications as a sustainable and functional biopolymer material. [ABSTRACT FROM AUTHOR]

Abstract This work deals with provision and characterization of the biopolymer-based composites achieved by incorporation of cellulose fibers as the reinforcement within the glycerol plasticized matrix formed by thermoplastic cornstarch biopolymer. The function of starch-based polymers is limited due to poor mechanical properties. However, it is improved with forming a biocomposite of thermoplastic starch (TPS) as matrix and the cellulose fibers (CF) as reinforcement. The surface of cellulose fibers is successfully modified using the air plasma treatment with the aim of improving the matrix/fiber adhesion. The modified fibers are studied using X-ray diffraction (XRD), scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). The TPS/CF composites are prepared using high friction and hot compression procedure. Tensile test results and SEM images of the fracture surfaces show significant improvement of adhesion between treated cellulose fibers and TPS matrix. Thermogravimetric analysis shows a considerable decomposition at approximately 250–350 °C. XRD proved the significant increase in crystallinity percentage of composites compared to TPS. [ABSTRACT FROM AUTHOR]

Disposable containers made of non-biodegradable polymers are considered as one of the most prevalent environmental pollutants. It is very important and desirable to make fully biodegradable disposable containers for food packaging that does not endanger the health of consumers. In this research, fully biodegradable polymer composites were prepared by melt mixing of polylactic acid (PLA), polybutylene succinate (PBS), and natural polymers including corn starch and wheat straw, and their physical and mechanical properties were evaluated. For this purpose, by conducting experiments according to the optimal custom mixture design of the response surface methodology, the effect of 3 independent variables including the concentration of the PLA and PBS biopolymers blend (50/50% w/w) (CBB) in the range of 30–70, the concentration of corn starch (CCS) in the range of 30–60 and the concentration of wheat straw (CWS) in the range of 0–8 wt percentage of biocomposite on the dependent variables including the elastic modulus (EM), elongation at break (EB), impact strength (IS) and equilibrium moisture content (EMC) of the biocomposite sheet were investigated. According to the results of this research, with the increase in the concentration of corn starch and wheat straw in the studied range, the EM and EMC of the biocomposite increased, while its EB and IS decreased. According to the results obtained from optimizing the effects of independent variables on the physicomechanical properties of the biocomposite sheet, the optimal values predicted by the models for CBB, CCS and CWS were 48.2 wt%, 45.4 wt%, and 6.4 wt%, respectively and predicted values for EM, EB, IS and EMC were 80.8 MPa, 11.4%, 2 kJ/m2 and 4.1%, respectively. Also, the biodegradability rate of the biocomposite with the optimal formulation was 71.1% in the fifth month of the test. • Biocomposites of biopolyester blend filled with two natural polymers were prepared. • Biocomposites contained polylactic acid, polybutylene succinate, starch, and wheat straw. • Constituents concentration had main effects on the sheet's physicomechanical properties. • Optimal sheet contains 48.2 wt% biopolyester blend and 51.8 wt% natural polymers. • The biocomposite sheet with optimal formulation had a high degree of biodegradability. [ABSTRACT FROM AUTHOR]

Gelatin biocomposites were successfully manufactured by extrusion followed by injection. The employment of these industrial techniques, which have not been widely used in the case of biopolymers such as gelatins, represents an important advance for the development of gelatin-based biocomposites. Furthermore, the use of a non-enzymatic reaction to cross-link proteins provides a new approach to improve and control some functional properties, such as solubility and swelling. The addition of lactose in the formulations, as well as the heating of injected biocomposites, caused gelatin cross-linking, changing the protein structure towards the formation of pores and thus, solubility, density, and swelling decreased. Additionally, the cross-linked biocomposites showed good mechanical properties. [ABSTRACT FROM AUTHOR]

Commingled plant and polypropylene fibres (PP) nonwovens are attractive for automotive industry because of their interesting mechanical performances combined with good acoustical properties. This double function is achieved thanks of controlled porosity within the composite material. Indeed, from a same material, different functions (acoustic or mechanical) can be obtained by only varying the compaction rate during moulding. This study aims to highlight the necessity of a very large porosity volume fraction (60%) to reach good acoustic properties and understand the mechanical effect behind it. By combining tensile testing, acoustic absorption measurement and scanning electron imaging analysis, the microstructure, acoustic and mechanical properties have been investigated and were found to be intimately related to the material porosity content. As expected, when increasing porosity level from 5 to 60%, the material behaviour change and its tensile properties (modulus, strength and elasticity domain) drop drastically to a point where the material is no longer elastic (70% porosity) due to a modification of the material microstructure involving different failure mechanisms. [ABSTRACT FROM AUTHOR]

Bacterial cellulose (BC) is recognized as a multifaceted, versatile biomaterial with abundant applications. Groups of microorganisms such as bacteria are accountable for BC synthesis through static or agitated fermentation processes in the presence of competent media. In comparison to static cultivation, agitated cultivation provides the maximum yield of the BC. A pure cellulose BC can positively interact with hydrophilic or hydrophobic biopolymers while being used in the biomedical domain. From the last two decades, the reinforcement of biopolymer-based biocomposites and its applicability with BC have increased in the research field. The harmony of hydrophobic biopolymers can be reduced due to the high moisture content of BC in comparison to hydrophilic biopolymers. Mechanical properties are the important parameters not only in producing green composite but also in dealing with tissue engineering, medical implants, and biofilm. The wide requisition of BC in medical as well as industrial fields has warranted the scaling up of the production of BC with added economy. This review provides a detailed overview of the production and properties of BC and several parameters affecting the production of BC and its biocomposites, elucidating their antimicrobial and antibiofilm efficacy with an insight to highlight their therapeutic potential. [ABSTRACT FROM AUTHOR]

Corn cob (CC) was used as a filler in chitosan (CS) biopolymer films. The effect of glutaraldehyde (GLA) as a crosslinking agent was studied in an effort to improve the properties of CS/CC biocomposite films prepared via solvent casting. The tensile strength and elongation at break values decreased, but the modulus of elasticity increased with CC content. However, the tensile properties of CS/CC biocomposite films improved when modified with GLA. The Fourier transform infrared (FTIR) results indicated the presence of imine bonds (C=N) and ethylenic groups due to the cross-linking reaction between CS and GLA. The thermal stability of CS/CC biocomposite films reduced with increasing CC content. The modification of CS/CC with GLA enhanced the thermal stability of the biocomposite films. Moreover, the wettability and adhesion of the CC-CS system were enhanced by modification with GLA, as demonstrated by a morphological study. The crosslinking agent glutaraldehyde positively affected the tensile strength, modulus of elasticity, and thermal stability of the biocomposite films. [ABSTRACT FROM AUTHOR]

Abstract: An Environmental Stress Cracking test was used to investigate damage to glass fiber reinforced poly(lactic acid) based biocomposites. The study was performed in water. The main advantages were a significant decrease in experiment duration compared to natural, artificial or accelerated tests and an increase in the reliability of the results. Depending on the specific nature of the glass fiber used, significant types of failure behavior were observed. [Copyright &y& Elsevier]

To control the swelling of sodium carboxymethylcellulose (CMCNa) membranes, mixtures of CMCNa and glutaraldehyde (GA) and mixtures of CMCNa as an organic component and tetraethoxysilane (TEOS) as an inorganic component were prepared, and CMCNa/GA cross-linked membranes and CMCNa/TEOS hybrid membranes were formed. In the separation of an ethanol/water azeotrope by pervaporation (PV), the effects of the GA or TEOS content on the water/ethanol selectivity and permeability of these CMCNa/GA cross-linked and CMCNa/TEOS hybrid membranes were investigated. Cross-linked and hybrid membranes containing up to 10 wt% GA or 10 wt% TEOS exhibited higher water/ethanol selectivity than CMCNa membrane without any cross-linker. This resulted from both increased density and depressed swelling of the membranes by the formation of a cross-linked structure. The relationship between the structure of the CMCNa/GA cross-linked membranes and CMCNa/TEOS hybrid membranes and their permeation and separation characteristics for an ethanol/water azeotrope during PV is discussed in detail. [ABSTRACT FROM AUTHOR]

Abstract: Adsorption of sulfide ions onto a surface of starch capped silver nanoparticles upon addition of thioacetamide was investigated. UV–vis absorption spectroscopy revealed that the adsorption of the sulfide ion on the surface of the silver nanoparticles induced damping as well as blue shift of the silver surface plasmon resonance band. Further increase in thioacetamide concentration led to shift of the resonance band toward higher wavelengths indicating the formation of the continuous Ag2S layer on the silver surface. Thus fabricated nanoparticles were investigated using electron microscopy techniques (TEM, HRTEM, and HAADF-STEM) and X-ray photoelectron spectroscopy (XPS), which confirmed their core–shell structure. [Copyright &y& Elsevier]

Abstract: In this work, a starch-based biopolymer was reinforced with flax strands. Composite materials at different fiber content were obtained by means of high-shearing mixing followed by injection molding processing. The evaluation of the mechanical properties gave a significant increase of the strength and stiffness of composites with the percentage of flax strands. The enhancement was analyzed in terms of compatibility and extension of the adhesion at fiber–matrix interface. The intrinsic mechanical properties of the reinforcement were measured and the behavior of the obtained composites was studied in terms of the modified rule of mixtures and the modified Halpin–Tsai equations. [Copyright &y& Elsevier]

Abstract: Thermoplastics reinforced by natural fibres are mainly used for fitting-up products in the automotive industry. The aim of this work is to study the tensile properties of natural fibre-biopolymer composites in order to determine whether or not, biocomposites may replace glass fibre reinforced unsaturated polyester resins. The materials used are flax fibre, polylactic acid (PLA), l-polylactide acid (PLLA), poly(3-hydroxylbutyrate) (PHB), polycaprolactone and starch thermoplastic (MaterBi® Z), poly(butylene succianate) (PBS) and poly(butylene adipate-co-terephtalate) (PBAT). The tensile properties of the flax fibres have already been determined [C. Baley, Analysis of the flax fibres tensile behaviour and analysis of the tensile stiffness increase, Comp Part A 2002;33:939–948]. The composites are manufactured using a film stacking technique. After studying the processing parameters, these are then adapted to each thermoplastic composites. Test samples are cut out from the composites to test their mechanical properties under tensile loading conditions. These tensile properties are then compared to those of similar polypropylene flax composites. Preliminary results show that the tensile properties are improved with the fibre volume fraction. The tensile strength and Young’s modulus of PLLA and PLA flax composites are greater than those of similar PP/flax fibre composites. The specific tensile strength and modulus of flax fibre/PLLA composite have proved to be very close to those of glass fibre polyester composites. [Copyright &y& Elsevier]

Insect cuticle as a natural biocomposite includes many favored microstructures which have been refined over centuries and endow the cuticle eminent mechanical properties. This paper first studies the microstructures of chafer cuticle through SEM observations. Several peculiar fiber configurations and fiber-ply arrangements such as branched fiber, acanth-fiber and helicoid plies are observed. These microstructures are useful for man-made fiber-reinforced composites to improve their mechanical properties. Then, a special configuration of the branched fiber found in chafer cuticle is in details analyzed through a mechanical model and experimental verification. The pullout force of fibers as an index is firstly studied through parameter study. The factors, which can improve the pullout forces, are identified. Finally, the maximal pullout force of the branched fiber is experimentally tested and compared with that of plain straight fiber. It is proved that the maximal pullout force of branched fibers is obviously greater than that of the plain straight fibers. [Copyright &y& Elsevier]

Over recent years, enthusiasm towards the manufacturing of biopolymers has attracted considerable attention due to the rising concern about depleting resources and worsening pollution. Among the biopolymers available in the world, polylactic acid (PLA) is one of the highest biopolymers produced globally and thus, making it suitable for product commercialisation. Therefore, the effectiveness of natural fibre reinforced PLA composite as an alternative material to substitute the non-renewable petroleum-based materials has been examined by researchers. The type of fibre used in fibre/matrix adhesion is very important because it influences the biocomposites' mechanical properties. Besides that, an outline of the present circumstance of natural fibre-reinforced PLA 3D printing, as well as its functions in 4D printing for applications of stimuli-responsive polymers were also discussed. This research paper aims to present the development and conducted studies on PLA-based natural fibre bio-composites over the last decade. This work reviews recent PLA-derived bio-composite research related to PLA synthesis and biodegradation, its properties, processes, challenges and prospects. [ABSTRACT FROM AUTHOR]

Fiber–matrix interfacial adhesion is one of the key factors governing the final properties of natural fiber-based polymer composites. In this work, four extrusion reactive agents were tested as potential compatibilizers in polyhydroxylbutyrate (PHB)/cellulose composites: dicumyl peroxide (DCP), hexamethylene diisocyanate (HMDI), resorcinol diglycidyl ether (RDGE), and triglycidyl isocyanurate (TGIC). The influence of the fibers and the different reactive agents on the mechanical properties, physical aging, and crystallization behavior were assessed. To evaluate the compatibilization effectiveness of each reactive agent, highly purified commercial cellulose fibers (TC90) were used as reference filler. Then, the influence of fiber purity on the compatibilization effect of the reactive agent HMDI was evaluated using untreated (U_RH) and chemically purified (T_RH) rice husk fibers, comparing the results with the ones using TC90 fibers. The results show that reactive agents interact with the polymer matrix at different levels, but all compositions showed a drastic embrittlement due to the aging of PHB. No clear compatibilization effect was found using DCP, RDGE, or TGIC reactive agents. On the other hand, the fiber–polymer interfacial adhesion was enhanced with HMDI. The purity of the fiber played an important role in the effectiveness of HMDI as a compatibilizer, since composites with highly purified fibers showed the greatest improvements in tensile strength and the most favorable morphology. None of the reactive agents negatively affected the compostability of PHB. Finally, thermoformed trays with good mold reproducibility were successfully obtained for PHB/T_RH/HMDI composition. [ABSTRACT FROM AUTHOR]