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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.

This study presents rice husk silica-reinforced elastomer composites fabricated by wet compounding, exhibiting 10% higher dynamic friction coefficients than the reference composites made by conventional dry compounding. Depending on the fabrication method, the filler micro-dispersion was characterized to correlate the measured friction coefficients with the viscoelastic properties with respect to sliding velocity and substrate lubrication. The effect of viscoelastic properties of the elastomer composites on the adhesion and hysteresis friction coefficients was investigated based on the elastomer friction theory. It was found that the constructed friction master curves showed a reasonable correlation with the theory. This study demonstrates that the rice husk silica can be used as a reinforcing filler for sustainable tires. More importantly, the well-dispersed filler microstructures can ensure the higher friction coefficients of the elastomer composites on rough surfaces, improving the tire performances (e.g., wet traction, cornering, and acceleration) of the ever-growing electric vehicles and future mobility.

Abstract Poly (butylene adipate-co-terephthalate)/thermoplastic starch (PBAT/TPS) blends and a PBAT/TPS/babassu mesocarp biocomposite were prepared by melt mixing in a torque rheometer at different processing temperatures (150, 170, 190 °C). Tensile test specimens were obtained by hot pressing. Torque rheometry indicated that molecular weight decreased with increasing processing temperature and TPS content in the blend, and this decrease was more intense with babassu mesocarp addition. PBAT mechanical properties were hardly affected by processing temperature while those of the blends decreased with thermoplastic starch content. Overall, increasing processing temperature led to lower mechanical properties, particularly at 190 °C. Fiber addition led to higher modulus and lower strength and elongation at break than the corresponding blend at all processing temperatures investigated. The differences observed on blend morphology as a function of processing temperature were minor. Some adhesion between TPS and PBAT is observed but adhesion between polymer matrix and babassu fibers is essentially non-existent. Highlights • PBAT/TPS and its biocomposite properties were processed at different temperatures. • Higher temperatures reduced the molecular weight of the samples. • PBAT properties were nearly insensitive to processing temperature. • Optimal properties were obtained for the samples processed at 170 °C with 20% TPS. • Babassu mesocarp showed low affinity with PBAT leading to lower elongation. [ABSTRACT FROM AUTHOR]

The purpose of this article is to understand the influence of typical composite parameters (interfacial bond strength, surface-area and fibre mechanical properties) on the tensile properties of nonwoven composite materials. The materials investigated were flax, hemp and Poly-(propylene) (PP) and Maleic Anhydride-grafted PP (MAPP), which provide different configurations in terms of fibre mechanical properties, bundle individualization and fibre/matrix interface. Whereas hemp fibres exhibit poorer tensile properties and lower bundle individualization than flax fibres, their higher lignin content evaluated by FT-IR analysis improves the interfacial shear strength (IFSS) with PP and MAPP. However, the tight interface developed with hemp fibres has only a weak effect at the scale of composites. With low-IFSS systems such as plant fibres associated with polyolefin matrices, mechanical properties at the macroscale are governed by the fibre mechanical properties and bonding area rather than by the interfacial bond strength. [ABSTRACT FROM AUTHOR]

Starch high biodegradation is a limitation for commercialization of starch derived slow release fertilizers (SRFs). To reduce starch biodegradation, kraft lignin (5%–20%) was tested for reducing the starch biodegradability in urea crosslinked starch (UcS) films, reported as here as a SRF. Biodegradability tests were conducted under anaerobic soil microcosm for period of 60 days. Fourier transformed infrared spectroscopy results showed an absence of peak at 1776 cm −1 (pertained to oxidation of starch) in biodegraded lignin reinforced films. Thermogravimetric analysis of lignin reinforced films showed deceleration in the biodegradability rates, which were clearly evident from increase in the decomposition temperature at 5% weight loss, ∼67.0 °C and at maximum weight loss, ∼13.6 °C. Besides, char contents were increased, ∼11.3%. Molecular weight distribution indicated the lignin's effect on conservation the molecular weight and polydispersity of starch in films. Lignin role in protecting the starch morphology was confirmed through optical microscopy results, which showed a less change for feret mean and particle area of starch particles. Further, lignin increased average roughness, ∼1.04 to 4.76 times for biodegraded films, possibly due to accumulation of lignin after loss of starch in films. Further, this study concluded that lignin influenced effectively the reduction in starch biodegradability under anaerobic soil microcosm. Thus, lignin could be used in urea crosslinked starch and other similar films, for controlling the starch biodegradability and improving the SRF formulations. [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]

A study of the impact behaviour and the post-impact residual strength of fully biodegradable composites is presented in this work. To this end, low-velocity impact tests and compressive residual strength tests were carried out on flax/PLA laminates. The results were compared with carbon/epoxy laminates, showing some important advantages in terms of absorbed energy and normalized residual strength. The reason was attributed to different energy absorption mechanisms; the main failure mode in flax/PLA laminates is fibre failure while residual strength of carbon/epoxy laminates is dominated by delaminations. [ABSTRACT FROM AUTHOR]

The production of ligno-cellulosic biomass-based composites requires the development of new methodologies to evaluate the reinforcement potential of a given biomass, such as miscanthus studied in the work. Miscanthus stems from thirteen genotypes were broken into elongated fragments and mixed with polypropylene composites in an internal mixer. The aim is to find the best protocol able to discriminate miscanthus genotypes for their reinforcement capability. The following process parameters were optimized in order to maximize the reinforcement effect of the stem fragment filler: mixing parameters (mixing time, rotor speed and chamber temperature), temperature, fragment content, size and length distributions and coupling agent. The relationship between the process parameters and the mechanical properties of composites were analyzed to evaluate the influence of genotype on reinforcement performance, showing the robustness of the protocol in effectively discriminating genotypes according to their reinforcing capacity. [ABSTRACT FROM AUTHOR]

This study presents rice husk silica-reinforced elastomer composites fabricated by wet compounding, exhibiting 10% higher dynamic friction coefficients than the reference composites made by conventional dry compounding. Depending on the fabrication method, the filler micro-dispersion was characterized to correlate the measured friction coefficients with the viscoelastic properties with respect to sliding velocity and substrate lubrication. The effect of viscoelastic properties of the elastomer composites on the adhesion and hysteresis friction coefficients was investigated based on the elastomer friction theory. It was found that the constructed friction master curves showed a reasonable correlation with the theory. This study demonstrates that the rice husk silica can be used as a reinforcing filler for sustainable tires. More importantly, the well-dispersed filler microstructures can ensure the higher friction coefficients of the elastomer composites on rough surfaces, improving the tire performances (e.g., wet traction, cornering, and acceleration) of the ever-growing electric vehicles and future mobility. • Wet compounding of rice husk silica/SBR composites ensured a good filler dispersion. • Wet-compounded rich husk silica/SBR composites exhibited 10% higher friction coefficient. • Constructed friction master curves showed a reasonable correlation with rubber friction theory. [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]

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]

The work outlines the synthesis of a new and easy technique to develop sustainable composites of sawdusts reinforced polyester resin composites. For shaping a new approach we have found very rare approach for developing composites with sawdusts of Mahagoni wood (Swietenia mahagoni) reinforced polyester resin composites in open literatures. Due to this gap, a plan made to develop untreated and treated sawdusts (very common in Bangladesh and many other countries of the world) reinforced strong and durable composites with unsaturated polyester resins along with their biodegradability, thermal and mechnical properties where the material properties were revealed and corelations were elaborated in the subsequent sections. Specifically, the tensile strengths of virgin resin (VR), untreated sawdust reinforced composite (UTSDC) and 4% caustic soda treated sawdust reinforced composite (4TSDC) are 10.77, 15.83 and 21.64 N/mm2, respectively. That means the observed reinforcement property for UTSDC and 4TSDC increased ~47% and 101%, respectively. Moreover, the binding phenomena were explained with the own schamatic presentation. The composite phenomena was explained sequentially by using Fourier transform infrared spectroscopy, scanning electron microscopy, thermogravimetric analysis, differential scanning calorimetry, X-ray diffraction, etc. Between the developed composites 4TSDC was strong (25% as compared from tensile strength) and durable (8% as observed in biodegradability results) than the UTSDC of unsaturated polyester resin. The pattern of water uptake follows usual Fickian diffusion behavior. The observed properties of the developed convincible composites indicate that they can be considered for indoor to outdoor applications especially for using the fence, roof, furniture items like chair, table, park benches, etc. • Sustainable composites of Swietenia mahagoni reinforced polyester resin composites have been developed. • Strong and durable composites along with their biodegradability are reported. • Thermomechanical properties and correlations with material properties were elaborated. • The pattern of water uptake follows usual Fickian diffusion behavior. • Developed convincible composites indicate suitable for indoor to outdoor applications. [ABSTRACT FROM AUTHOR]

The effect of cassava pulp (CP) on morphological, tensile, and thermal properties of a thermoplastic cassava starch (TPS)/poly (lactic acid) (PLA) blend was investigated. TPS/PLA/CP biocomposites were manufactured by melt extrusion and then converted into specimens using an injection molding. The weight fraction of PLA to TPS/CP was fixed at 40:60, whereas the final CP concentration in the composites was varied in the range of 4.4–22.1 wt%. CP could act as a reinforcement for TPS/PLA blend to enhance its tensile strength up to 354% and Young's modulus up to 722% when 22.1 wt% of CP was loaded and a nucleating agent for PLA as confirmed from the reduced T cc. In addition, TPS/PLA/CP composites showed a discrete phase structure (i.e., droplets in matrix) when CP with lower concentration (i.e., 4.4 wt%, 8.8 wt%, and 13.3 wt%) was incorporated and a bicontinuous phase structure (i.e., co-continuous) when higher concentration of CP (i.e., 17.7 wt% and 22.1 wt%) was employed. The results suggest that TPS/PLA/CP biocomposites have potential to be used in the manufacturing of injection-molded articles, particularly when biodegradability and renewability of the material are required. • Thermoplastic starch/poly (lactic acid)/cassava pulp (TPS/PLA/CP) composites were produced by melt extrusion. • CP could act as a reinforcement to enhance tensile strength and Young's modulus of the composites. • CP could act as a nucleating agent for PLA in the composites as confirmed from the reduced T cc. • The composites showed a discrete phase structure when CP with lower concentration was loaded. • Co-continuous phase structure was observed for the composites with higher concentration of CP. [ABSTRACT FROM AUTHOR]

Tissue engineering uses some engineering strategies for the reconstruction and repair of the compromised tissues, among which the use of biomaterials as an alternative to conventional transplants is significant. However, not many research has been developed on the use of biopolymer nanostructure microanalysis and calcium phosphate composites of carbon apatite in PLA as scaffolds for tissue regeneration. In this work, poly (lactic acid) filaments with 5% and 20%, carbon apatite (cHA) were microanalysis to produce a 3D printing scaffold. The scaffolds were characterised by the Scanning Electron Microscope (SEM) and Energy Dispersive X-Ray (EDX) techniques, thereby making it possible to notice a good load dispersion. The microstructural analysis of the scaffolds was carried out by computerised micro-tomography to determine the roughness, morphological parameters of pore size distribution, porosity, as well as better visualisation of the distribution of particles. A computational in vitro and microanalysis tests to assess the biocompatibility viability of the PLA/cHA structure with a variation of scaffold geometry to evaluate their effects on morphological, physicochemical and mechanical properties were also carried out. The characterisation of Ca and P release assays were observed for longer incubation times and the dynamic condition control to simulate the stresses suffered by the biomaterial exerted by the flow of fluids was achieved. The results obtained indicated that the micrographs of the cross-sections of the scaffolds showed a flatness in the loaded material when compared to the 100/0 PLA. Furthermore, the apparent porosity of 5% and 20% of cHA scaffolds gave a porosity percentage of approximately 62% and 41% respectively. The reduced summit height, reduced valley depth and the percentage upper and lower bearing area difference of the samples are 16.33 nm, 9.62 nm and 75.07% respectively. The morphological characterisation surface roughness analysis and tolerance insertion gave a favourable reduced porosity result for the composite scaffolds with 5% of cHA. Hence, this work will assist biomaterial industries in the development of biomaterials which have been engineered with biological systems to meet medical purposes. • To mimics biomaterial composites used for bone implant through the gradual PLA/CHA biocomposite. • Investigated mechanical, chemical, physical properties of the biomaterial in three aggregates. • Microstructural analysis of PLA/CHA scaffolds by computerized micro-tomography for roughness, morphological. • Assessment of the hybrid scaffolds done by surface roughness evaluation, mechanical and bioactivity analysis tests. [ABSTRACT FROM AUTHOR]

This study investigates the evolution of hygromechanical properties of flax/PP nonwoven composites in a wide range of environmental Relative Humidity (RH) conditions from 10 to 98% RH. The influence of microstructure with various porosity content (Φ = 5, 30, 50%) on the mechanical and hygroscopic behaviours is studied and compared to glass/PP composites as a baseline. No significant changes in the moisture content and mechanical properties of glass-fibre reinforced composites are observed. For flax fibre nonwoven composites, the porosity greatly impacts the kinetic of sorption with moisture saturation varying from 9 h to 15 days with decreasing voids. Hygroscopic expansion is hardly modified by the porosity content while anisotropic expansion is always observed. Tensile behaviour and properties are slightly changed over a range of 10–75%RH but negatively impacted between 75% and 98% RH. Interestingly, unlike the tangent tensile modulus and strain at rupture of flax/PP composites, the yield strength exhibits a non-monotonic trend with an optimal value over 50% RH; compressive stresses at the fibre/matrix interface induced by flax fibres hygroexpansion are proposed to explain this trend. • Evolution of hygromechanical properties of flax/PP non-woven composites was investigated. • A large range of porosity (5, 30, 50%) and humidity (10–98%) was explored. • The kinetic sorption behaviour was greatly impacted by porosity content. • Tensile behaviour and properties are slightly changed over a range of 10–75%RH. [ABSTRACT FROM AUTHOR]