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Various treatments, such as alkaline and silane treatments, are commonly applied to natural fillers before production to enhance their quality, thermal stability, and water absorption capacity and improve the fiber–matrix interface properties. However, these processes are not environmentally friendly and may escalate the production cost of composites due to the need for additional processing steps in mass production. This study delves into the impact of untreated walnut shell (WS) filler material, employed in varying ratios (ranging from 10 to 40%) as a filler, on the mechanical, thermal, morphological, and physical properties of environmentally friendly polylactic acid (PLA) matrix composites. The experimental results highlight a significant decrease in tensile modulus by 28%, tensile strength ranging from 32 to 65%, a decrease in flexural modulus by 22%, and flexural strength ranging from 24 to 58% with varying WS filler ratios. Time-dependent water absorption and increased density were observed. FT-IR analysis indicates structural similarities, while DSC results show minimal effects on glass transition temperature and crystallinity. TGA results reveal reduced thermal stability with increasing WS content. SEM microstructure imaging demonstrates homogeneous WS particle distribution, but higher WS content leads to increased brittleness and diminished resistance properties. In conclusion, this study underscores the importance of balancing sustainability through WS filler ratios while preserving mechanical performance. [ABSTRACT FROM AUTHOR]

The main advantage of green composites is their biodegradability, but this biodegradability can also be considered a drawback if the degradation appears during the service life of the component. Therefore, the study of the mechanical behavior of green composites after hygrothermal aging tests is necessary to analyze their degradation process. This study aims to comprehensively analyze the hygrothermal aging behavior and aging mechanism of flax-fiber-reinforced polylactic acid (PLA) biocomposites. The fully biodegradable composites are manufactured by compression molding. In addition, the influence of atmospheric-pressure plasma treatment on the mechanical properties of the biocomposite is studied. Specimens are exposed to water vapor and 40 °C environmental conditions in a stove for up to 42 days. Several specimens of each type are taken out at regular intervals and tested to examine the water absorption, mechanical properties, and thermal characterization. The results show that the stiffness was significantly reduced after 24 h due to matrix degradation, while the strength was reduced only after three weeks. [ABSTRACT FROM AUTHOR]

Biocomposites based on polylactic acid (PLA), tall wheatgrass (TWG), and hemp (H) were made by injection molding. The article discusses the impact of the agrofiller content on the composite properties, including thermal (DSC, DMA, and TG) and mechanical characteristics (tensile modulus, tensile strength, and impact strength). Generally, the introduction of a plant filler into the polylactide matrix reduced the thermal resistance of the resulting composites. Plant fillers influenced primarily the cold crystallization process, probably due to their nucleating properties. The addition of fillers to the PLA matrix resulted in an increased storage modulus across all tested temperatures compared to pure PLA. In the case of a composite with 50% of plant fillers, it was almost 118%. The mechanical properties of the tested composites depended significantly on the amount of plant filler used. It was observed that adding 50% of plant filler to PLA led to a twofold increase in tensile modulus and a decrease in tensile strength and impact strength by an average of 23 and 70%, respectively. It was determined that composites incorporating tall wheatgrass (TWG) particles exhibited a slightly elevated tensile modulus while showcasing a marginally reduced strength and impact resistance in comparison to composites containing hemp (H) components. [ABSTRACT FROM AUTHOR]

The fractionation of diatomaceous earth (DE) using sedimentation made it possible to obtain separate unbroken diatom fractions from broken or agglomerated bodies with a range of particle sizes. The produced filler was used to prepare polylactide (PLA)/diatomaceous earth biocomposite samples containing different particle sizes, which were subjected to mechanical testing (tensile strength, flexural strength, impact strength), colloidal testing (contact angle, color change test, SEM/EDS), and thermal testing (TGA, DSC, DMA). Modification of the PLA containing the smallest particle size with diatomaceous earth (Fraction 5) resulted in a higher impact strength compared to both the pure PLA and the PLA/DE composite that contained base diatomaceous earth. Furthermore, the melt flow rate was improved by more than 80 and 60% for the composite modified with fractionated diatomaceous earth (Fraction 4) compared to pure PLA and base diatomaceous earth, respectively. The elasticity of the composite was also improved from 3.3 GPa for pure polylactide to 4.4 GPa for the system containing the smallest diatomaceous earth particles (Fraction 5). [ABSTRACT FROM AUTHOR]

This research was performed to evaluate the physical, mechanical and morphological properties of sugar palm fiber (SPF) reinforced polylactic acid (PLA) composites. PLA is a thermoplastic biodegradable polymer which is mostly used as a matrix material in the composite. Sugar palm fiber and PLA were mixed to form composite compounds using twin-screw extruder. These biocomposites of various sugar palm fiber loads (0, 10, 20, 30, and 40 wt. %) were prepared by using compression moulding. The effect of the loading of sugar palm fibers on the physical properties of composites (density, voids, and water absorption analysis), mechanical (tensile, flexural, and impact analysis) and morphology was studied. The determination of water absorption at different fiber loadings showed that the percentage of water absorption increased as the loading of fibers increased. The 30 % SPF loading composite displays optimum values for flexural and tensile strength which are 26.65 MPa and 13.70 MPa, respectively. Morphological studies by scanning electron microscopy revealed homogeneous fiber and matrix distribution also at 30 % loading of SPF with excellent adhesion, which plays an important role in enhancing the mechanical properties of composites. SEM analyzes show strong dispersion of SPF into PLA matrix. [ABSTRACT FROM AUTHOR]

Biocomposites of waste polypropylene (wPP) with 20 phr (part per 100 parts of [wPP]) corn husk fibers (CHF) as bio-filler were prepared for environmental aspect. Maleic anhydride (MAH) was used, with 5, 10 phr concentration as compatabilizer was carried out. The obtained biocomposites were irradiated by γ radiation ranging from 5 to 25 kGy. Mechanical, physical and thermal properties of the biocomposites were studied to evaluate the effect of CHF addition on the properties of obtained composites. It has been found that there is deterioration in all properties. However, by the addition of MAH, the former properties were improved. The obtained results were confirmed by Fourier transform infrared (FTIR) and scanning electron microscopy (SEM). [ABSTRACT FROM AUTHOR]

• The mixture of boric acid and borax slow down PLA's fire speed by roughly 66 %. • Thermal degradation temperature lowered by the addition of boron compounds to PLA. • Flexural and Young's modulus prominently rise by roughly 20 % and 22 %, respectively. • 5 wt% boron compounds reinforced composites have better mechanical–thermal results. This study aims to understand how ulexite, boric acid-borax mixtures (1:1), and zinc borate fillers affect the thermal and mechanical properties of the poly (lactic acid) (PLA). For this purpose, three different boron fillers were added to the PLA matrix at four different concentrations of 3 %, 5 %, 8 %, and 12% wt. UL-94 test was conducted to comprehend the impacts of boron fillers on the fire resistance of the biocomposites. Thermogravimetric analysis was applied to determine the thermal stability, mass loss, and decomposition temperature of the samples. The biocomposite's significant mechanical properties, such as tensile strength, flexural strength, Young's modulus, and elongation at break, were assessed using tensile and three-point bending tests. Although the tensile and flexural strengths of PLA reduced, flexural and Young's modulus rose by roughly 20 % and 22 %, respectively, with rising boron filler rates. [ABSTRACT FROM AUTHOR]

Office wastepaper fibers(OWF)/poly(butylene adipate-co-terephthalate) (PBAT)/poly(lactic acid) (PLA) biodegradable composites with different mass ratio were made by melt blending and injection moulding process. At the same time, the use of MAPLA and KH560 was studied as a potential approach for improving interfacial adhesion between OWF, PBAT and PLA. The results revealed that with the increasing of PBAT, the notched impact strength of PLA/PBAT/OWF composites can be first increased and then decreased. When the content of PBAT was 20 wt%, the notch impact strength of PLA/PBAT/OWF composite was the highest, increased by 291% compared with pure PLA. TGA results revealed that the onset degradation temperature of the composites can be increased and its thermal decomposition step can be changed. According to the crystallization and melting performance table, OWF can act as nucleating agent to promote the crystallization properties of composites, while PBAT can prevent the crystallization and the higher the content is, the more obvious it is. It can be seen from the SEM figures that the addition of MAPLA and KH560 simultaneously makes the composites interface bond closer, thus improving the interface performance of PLA/20PBAT/OWF composite. Among the three kinds of modified composites, PLA/20PBAT/OWF/MK composite has the lowest water absorption and the best comprehensive performance. [ABSTRACT FROM AUTHOR]

In this work, cellulose nanoparticles (CNP) reinforcement on synthetic rubber (SR)/polylactic acid (PLA) blend was investigated. Initially, SR/PLA blend was prepared by varying SR from 5 to 20 wt%. Later, a fixed amount (3 wt%) of CNP was added and resulting effect on mechanical, thermal, and dynamic properties was studied. The results show the addition of CNP in SR/PLA blend resulted in ~147 and ~196% improvement in tensile strength and storage modulus, respectively. In addition, impact strength of SR/PLA blend was almost doubled after CNP incorporation. An improvement of ~4.5% in the thermal stability of SR/PLA was also observed. [ABSTRACT FROM AUTHOR]

This work deals with fibrous biocomposites prepared by using nettle and poly(lactic acid) fibers and employing carding and compression-molding processes. The role of carding process in determining the tensile strength of the biocomposites was analyzed. The tensile, bending and impact properties of the biocomposites were found to increase initially with the increase of nettle fiber content till 50 wt% and decrease afterwards. The thermogravimetric analysis inferred that the thermal stability of the biocomposites increased with the increase of nettle fiber content. The dynamic mechanical analysis showed that the biocomposites exhibited high storage modulus, low loss modulus, and low damping factor. Further, the biocomposites exhibited excellent biodegradability and their biodegradability increased with the increase of nettle fiber content. Overall, the biocomposite prepared with equal weight proportion of nettle and poly(lactic acid) showed high potential for automotive dashboard panel application. [ABSTRACT FROM AUTHOR]

Natural fibers are not as rigid as glass or carbon fibers. During composites extrusion and injection molding, they tend to bend and twist in the polymeric matrix, thus resulting in fiber waviness and decreased mechanical properties of natural fiber composites. The most widely used models for the estimation of interfacial shear strength (IFSS) and elastic modulus, which consider the fiber aspect ratio and mechanical properties of the fiber and matrix, do not consider these important features. In order to account for fiber waviness, an effective fiber length is proposed in this paper. The undulation of the fibers is approximated with a sinusoidal arc along with a calculated new length. The proposed correction factor depends on the wavelength and amplitude of the wave approximating the fiber. To verify this method, blends of polylactic acid (PLA) and polycarbonate (PC) (prepared with and without an interchange reactions catalyst) with addition to various percentages of cellulosic fibers (5 wt%, 10 wt% and 15 wt%) have been prepared and characterized. It has been demonstrated that by considering the corrected length values, it is possible to predict the mechanical properties and the effective reinforcement attained in the composites by using the most widely used models. In particular, the prediction of the elastic modulus is slightly affected by this correction, whereas the calculation of IFSS is strongly dependent on it. [ABSTRACT FROM AUTHOR]

This work aims the manufacture of injection molded polylactic acid (PLA)-based magnetic biocomposites, presenting an alternative approach to enhance the magnetic susceptibility of PLA-based biocomposites without resorting to the exclusive incorporation of magnetic nanoparticles whose long-term side effects are still unclear. Magnetic biocomposites were obtained by incorporating 5 wt% of iron doped biphasic calcium phosphate (FeBCP) powders into the PLA matrix and compared with similar composites containing 2 and 5 wt% of non-doped BCP powder, as well as neat PLA. The chemical, thermal, mechanical, and magnetic performances were evaluated. Biodegradability according to two sterilization methods used and cytotoxicity were also assessed. The composites with FeBCP exhibited a typical ferromagnetic-like behavior and presented a superior tensile strength even with low concentrations of FeBCP, when compared to PLA or non-doped composites, besides being cytocompatible. The presented proof of concept paves the way for future developments of new magnetic PLA-based biocomposites for biomedical applications. [Display omitted] • New generation of magnetic PLA-based composites preventing the use of MNP. • Magnetic BCP powders improved the mechanical performance of PLA-based composites. • Homogeneous distribution of magnetic BCP-based powders within PLA matrix was attained. • BCP powders improved the thermal stability of PLA. [ABSTRACT FROM AUTHOR]

Environmental awareness of the global waste problem has driven the development of new green composites made from either renewable or biodegradable materials. Among the variety of available green composites, natural composites based on poly-lactic acid (PLA) have shown noteworthy performance due to their short degradation time after disposal, good strength, and ease of processing by conventional methods. In particular, green composites manufactured with PLA matrix reinforced with Manicaria Saccifera fabric (MF) display mechanical properties that have shown to be very competitive compared with similar materials. In this study, the tensile properties of a green composite of PLA reinforced with MF are optimized by using a Taguchi method approach. The processing parameters, fabric chemical treatment parameters, compression molding parameters, and fiber content are analyzed simultaneously to yield the optimum biocomposite properties. The predicted optimum parameters are experimentally verified. Tensile tests and scanning electron microscope (SEM) analysis are used. Significant improvements on both the tensile strength (114.2%), and the elastic modulus (120.6%) of the biocomposite are achieved. [ABSTRACT FROM AUTHOR]

The motive of this study is to lessen the dependence on non-degradable plastic packaging by developing alternative material; reinforced poly(lactic acid) (PLA) with kenaf fiber (KF) biocomposite using available plastic processing machineries. For that reason, this study focuses on fabrication of PLA–KF biocomposite using intermeshing co-rotating twin-screw extruder and then injection molded for mechanical characterization. The effect of KF loading from 0 to 20 wt% was studied. No coupling agent was added due to high affinity of PLA and KF and both components are hydrophilic in nature. The average of KF aspect ratio is 30. Tensile properties and flexural properties show similar trend where significant improvement was attained at 20 wt% KF content. Scanning electron micrograph of tensile fracture specimen has revealed the hypothesis of interaction between fiber and matrix which subsequently amplified the tensile properties. It is an interesting finding where the experimental value of tensile modulus was 15% higher than theoretical tensile modulus at 20 wt% KF. Additionally, PLA–KF bicomposite produced, has high specific strength and specific modulus. This could suggest that KF may be incorporated into PLA to reduce mass of the end product and substantially reduce the cost of raw materials. As expected, impact strength however decreases with KF content. [ABSTRACT FROM PUBLISHER]

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]

Recycled polylactic acid (PLAr) was reinforced with treated nanocellulosic hemp fibers for biocomposite fabrication. Cellulosic fibers were extracted from hemp fibers chemically and treated enzymatically. Treated nanocellulosic fibers (NCF) were analyzed by Fourier-transform infrared spectroscopy, X-ray diffraction, and scanning electron microscopy. Biocomposite fabrication was done with PLAr and three concentrations of treated NCF (0.1%, 0.25%, and 1% (v/v)) and then studied for thermal stability and mechanical properties. Increased thermal stability was observed with increasing NCF concentrations. The highest value for Young's modulus was for PLAr + 0.25% (v/v) NCF (250.28 ± 5.47 MPa), which was significantly increased compared to PLAr (p = 0.022). There was a significant decrease in the tensile stress at break point for PLAr + 0.25% (v/v) NCF and PLAr + 1% (v/v) NCF as compared to control (p = 0.006 and 0.002, respectively). No significant difference was observed between treatments for tensile stress at yield. [ABSTRACT FROM AUTHOR]

The compound of poly(lactic acid) (PLA) and cellulose was made by the emulsion-solvent evaporation technique in order to obtain spheres which are then compression molded to produce a biocomposite film. The effect of the dispersant (poly(vinyl alcohol)—PVA)/PLA ratio on the spheres yield was studied. Moreover, to evaluate the effect of cellulose particle size and surface chemistry on the process yield, unbleached eucalypt kraft pulp and microcrystalline cellulose (MCC), both unmodified and physically or chemically modified were used. PLA/cellulose spheres were characterized regarding its physical properties. It was found that the spheres yield is essentially determined by the PVA/PLA ratio and the percentage of cellulose incorporation is greatly affected by the surface chemistry of cellulose. Regarding the films, DSC runs showed a significant effect of the cellulose type incorporated into PLA matrix on the cold crystallization temperature and on the degree of crystallinity of the biocomposite films. The measurement of tensile properties of the biocomposite films revealed that the strength, elongation at break and toughness (tensile energy absorption at break) of the films incorporating unmodified and chemically modified MCC were substantially improved. [ABSTRACT FROM AUTHOR]