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Fiber-reinforced green composites made from natural plant fibers are an increasingly popular sustainable alternative to conventional high-performance composite materials. Given the variety of natural fibers themselves, and the even larger variety of possible composites with specific fiber dosage, fiber orientation distribution, fiber length distribution, and fiber–matrix bond characteristics, micromechanics-based modeling is essential for characterizing the macroscopic response of these composites. Herein, an analytical multiscale micromechanics model for elastic homogenization is developed, capable of capturing the variety. The model features (i) a nanoscopic representation of the natural fibers to predict the fiber stiffness from the universal stiffness of the fiber constituents, mainly cellulose, (ii) a spring-interface model to quantify the compliance of the fiber–matrix bond, and (iii) the ability to model any (and any combination of) orientation distribution and aspect ratio distribution. Validation is performed by comparing the predicted stiffness to experimental results for as many as 73 composites available in the literature. Extensive sensitivity analyses quantify the composite stiffening upon increasing fiber volume fraction, fiber alignment, fiber length, and fiber–matrix interface stiffness, respectively. [ABSTRACT FROM AUTHOR]

Bioinorganic cations, that actively involved in many vital cellular activities, have been highlighted in regeneration and repair of tissues recently. However, researchers are still exploring how the sophisticated regulation of these bioactive factors within the microenvironment contribute to the process. Here, we established magnesium oxide homogeneously- and heterogeneously-embedded biocomposites to investigate the biological impacts that result from the different aggregation structure of the bioinorganic element. On the heterogeneous biocomposite, unbalanced microenvironment with erratic ion niche was provided, while stable ionic microenvironment was shown on the homogeneous biocomposite. Compared with the ionic micro-homeostasis, the heterogeneous micron-cluster-created unbalanced niche compromised cellular adhesion and proliferation by restraining the membrane extensions and downregulating the expression of proliferative genes. This unbalanced niche also motivated nonactivated macrophage polarized towards pro-inflammatory phenotype and induced high ratio of necrotic cell death by increasing the intracellular oxidative stress and decreasing the ATP content. After implantation, the homogeneous scaffold promoted tissue healing, whereas the immune responses were deteriorated and prolonged by heterogeneous scaffold, which leading to impaired bone regeneration. This study demonstrated the importance of biocomposite-established magnesium ionic micro - homeostasis on bone tissue regeneration and may inspires the future development of biomaterials. [Display omitted] [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]

Abstract Porosity of scaffolds plays an indispensable role in tissue regeneration. In this paper, hierarchical scaffolds with tailored macro/micro-porosity architectures for bone tissue engineering applications were introduced. Poly (vinyl alcohol) (PVA) has been innovatively blended into poly (lactic acid) (PLA) to fabricate composite filaments for fused deposition modeling (FDM). Customized macropores (pore size > 100 μm) of scaffolds were designed and precisely fabricated by FDM process. Then the blended scaffolds were subjected to gas foaming process to create micropores (pore size < 10 μm), which are hardly created by using 3DP techniques. Subsequently, PVA phase in the scaffolds was extracted by solvent etching method to create open pores, which are hard to create in gas foaming. The results showed that the scaffolds with 100–800 μm macropores can be precisely fabricated by FDM technique. Meanwhile, 2–10 μm micropores were successfully created. These novel scaffolds have the potential to be used in bone tissue regeneration. [ABSTRACT FROM AUTHOR]

The suitability of three local lignocellulosic wastes i.e. almond shell (AS), rice husk (RH) and seagrass (SG) as fillers in PHB/Fiber composites applications has been studied. PHB/Fiber composites with 10 phr and 20 phr fiber content were prepared by melt blending. The influence of the fiber type (size, morphology and origin) and content on the morphological, mechanical and thermal properties of the as obtained composites has been assessed. To evaluate the potential use in food packaging applications, the barrier performance to water, thermoforming ability and disintegration in controlled composting conditions of the composites were also studied. All the fibers have demonstrated to be apt for their use as fillers in PHB/Fiber composites, showing a reinforcing effect without affecting the crystallinity and the disintegration rate of PHB. The thermal stability and the water barrier performance of the composites were reduced by the presence of the fibers. Nevertheless, the addition of AS resulted in the best balance of properties, in terms of permeability and mechanical properties, finding an enhancement of the thermoforming ability of PHB when 10 phr of AS was added. [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]

The manufacture of mycelial matrix biocomposite and vegetable reinforcement involves control of the substrate proportion, choice of isolate and drying conditions. The objective of this study was to analyze the impact of different drying heat treatments on the mechanical, physical, chemical and thermal responses of the biocomposite composed by the fungal isolate Pycnoporus sanguineus associated with coconut powder and wheat bran. The mycelium grew randomly on the substrate, degraded it and acted as a binder between the particles. In addition, a dense and compact mycelial network was formed on the surface. The time and temperature significantly affected physical, mechanical properties and microstructure of the biocomposite. Overall, a lightweight biocomposite was obtained with a compressive strength between 134 and 200 kPa. [ABSTRACT FROM AUTHOR]

The author presents the new possibilities of use polymer sulfur material applied as industrial waste in biomaterials. Specific chemical environments step out in the environment in alive organisms. Metal parts of endoprostheses have a detrimental effect on the bones that come into contact with them and on the entire body patient. There are certain chemical environments in living organisms. The animal organism is a corrosive environment for metal endoprostheses. Metal parts of endoprostheses undergo chemical and electrochemical corrosion. Elemental sulfur should be a biocompatible material. Experimental studies have shown that the waste of polymerized sulfur is a biocompatible material. The waste of polymerized sulfur creates new possibilities for the production of biomaterials for surgical applications. Polymer sulfur composite currently has several interesting applications in the construction industry. It seems that one of the most interesting applications may be a polymer biocoating for metal implants. The first results of experimental studies showed that the waste of polymerized sulfur can be used as a biocomposite. [ABSTRACT FROM AUTHOR]

Herein, we used intense shear to construct caterpillar-like continuous hierarchical fibers (CLCHF). This architecture was then modified with mussel inspired poly(dopamine) (PDA) and γ-methacryloxypropyl trimethoxy silane (KH570) in a one-step method. Finally, employing (PDA + KH570)@CLCHF and compounded with poly(butylene succinate) (PBS) ultrafine fiber, (PDA + KH570)@CLCHF/PBS biocomposite was manufactured by combining intense shear and thermal-compression method. In virtue of intense shear, CLCHF can be effectively produced with nanoscale fibrils from 2 nm to 28 nm and (PDA + KH570)@CLCHF and PBS ultrafine fibers displayed favorable homogenization in aqueous solution. More importantly, the interspace between (PDA + KH570)@CLCHF and PBS ultrafine fibers could be optimized to facilitate infiltration at high filler content in polymers. The results also showed that the PBS biocomposite with 30 wt% (PDA + KH570)@CLCHF displayed optimal mechanical performance. Its tensile strength, elastic modulus, flexural strength, flexural modulus and impact strength reached to 120.2 MPa, 6.4 GPa, 110.1 MPa, 4.0 GPa and 23.5 kJ/m2, respectively. It is noticeble that the tensile properties were superior to some previously reported PBS biocompoistes due to the ability of CLCHF to effectively hinder the aggregation of numerous microcracks and slow crack tip propagation. The (PDA + KH570)@CLCHF/PBS biocomposites reported here can be used as desirable substitutes for nondegradable composites due to its high value added and favorable mechanical performance, and may broaden the application prospect of PBS biocomposite. [ABSTRACT FROM AUTHOR]

Proteins-polysaccharide scaffolds have been attracted extensive attentions in tissue engineering for decades. However, degradation of these biocomposites are still unknown owe to their difference in hydrophilicity, pore morphology, density and crystallinity, which obviously limits their applications. Here, we designed a silk fibroin/hyaluronic acid (SF/HA) nerve conduit with oriented channels, combining with different components and HA interpenetrating network to improve stability and biodegradation of the conduit. The conduit exhibited well-organized porous structure, remarkable flexibility, water absorption and stability (<8%), determined by morphology and solubility tests. The structure analysis showed that the silk I structures are dominant of the SF/HA conduits. The drug release behavior of the conduits demonstrated gradient release of rhodamine B with an attribute to the oriented channels. Further, by HA skeleton of interpenetrating network, the SF/HA conduits retained conduit and porous morphology in protease XIV solution for 21days. More importantly, the conduits showed good biocompatibility, which are verified by the growth and phenotype of mouse embryonic stem cell. This study broadening the understanding of the biodegradation behavior of protein-polysaccharide biocomposites and provides promising design strategy for nerve conduits. • Protein-polysaccharide conduits with multichannels were fabricated successfully by freezed drying technique. • Hyaluronic acid acted as skeleton of interpenetrating network against biodegradation of the conduits. • The conduits exhibited gradient drug release, good biocompatibility and potential for nerve tissue engineering. [ABSTRACT FROM AUTHOR]

Advanced biocomposites reinforced by abundant biomass-derived fillers can add a revenue stream to enhance the economic viability of biofuel production chains and the energy efficiency of the composite industry. However, the low stiffness of biopolymers limits their use in structural applications. Poplar fibers (mesh size: <180 μm, Populus spp.), an abundant waste from the wood industry, were used as bio-filler to fabricate high-performance biocomposites based on polylactic acid (PLA), in which the poplar fibers were modified by an amino acid (l -lysine). As a benefit of the amino acid treatment, the tensile Young's moduli of the lysine/poplar/PLA composites increased by up to 68% with the addition of a small amount of lysine, compared with neat PLA. At the same time, the tensile strength, failure strain, and Young's modulus of the poplar/PLA composites all increased after adding only 0.1 wt % of lysine. It has been observed that the lysine content has a significant effect on the decomposition temperature, complex viscosity, storage modulus, crystallization temperature, and crystallinity of composites. The fracture surfaces of the composites with an optimum lysine content had fewer voids and were more compact compared with composites without any lysine. The pores on the surfaces of poplar fibers became more available for the penetration of PLA molecules as a result of lysine addition. Therefore, this study presents a facile method for reinforcing biocomposites with extremely low-cost and environmentally friendly biofillers. Image 1 • A small amount of amino acid improved the fiber/PLA interfacial adhesion. • Poplar/PLA composites with 0.1 wt% lysine exhibited best tensile strength and modulus. • Poplar/PLA composites with 0.1 wt% lysine exhibited superior rheology for 3D printing. • A proposed mechanism in composites: chain extension, cross-linking, and degradation. [ABSTRACT FROM AUTHOR]

Biodegradable poly(lactic acid) (PLA) presents suitable physicochemical properties and biocompatibility for biomedical engineering. However, PLA has some drawbacks, such as low cell adhesion, biological inertness, low degradation rate, and acid degradation by-products. In this review, recent progress on strategies to address these problems is summarized, including novel fabrication techniques, high-performance PLA composites, and their applications for tissue engineering and drug delivery. The scaffolds, especially for bone regeneration, blood vessels, organs, and skin regeneration are evaluated, in terms of in vivo and in vitro biocompatibility and biodegradability. The enhanced mechanical, thermal, and rheological properties of PLA biocomposites are analyzed in detail. PLA biocomposites for drug encapsulation, sustained release, and tumor-targeting are also reviewed. Furthermore, the challenges and future perspectives on PLA-based biocomposites are discussed. [ABSTRACT FROM AUTHOR]