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Bioplastics and biocomposites are eco‐friendly alternatives to their petrochemical derived commodity material, but tend to have inferior mechanical and thermal properties. In this work, short‐fiber self‐reinforced bioplastic composites (SRBCs) have been developed that seek to overcome some of these shortcomings. The SRBCs leverage melt‐spun drawn poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate) (PHBV) fibers with axially‐oriented crystalline structures that exhibit a ≈6.7 °C higher melt temperature than the same PHBV in isotropic form. This enables a controlled‐temperature compounding process that preserves the crystalline structure of the fibers without distortion and ensures uniform distribution within the matrix. The resultant composites display a ≈35% increase in ultimate tensile strength and a ≈55% increase in impact resistance compared to neat PHBV polymer. This monolithic‐type composite system, characterized by high interfacial compatibility and strong fiber‐matrix adhesion, also supports high‐value recycling while preserving its mechanical properties across multiple lifecycle uses. By focusing upon discontinuous short fiber reinforcement, this work provides unprecedented opportunities for scaling SRBCs through commodity application pathways such as injection molding, compression molding, and 3D printing.

In this review paper, recent developments in the Fused Filament Fabrication (FFF) approach are provided for composite materials. Influencing parameters in FFF process such as road width, print speed, layer thickness, feed rate and build temperature of the model (both liquefier and envelope temperature), fiber orientation, the layer position, volume fraction, and infill orientation have been studied. These considered parameters in the strength/bonding or physicochemical characterizations of FFF-fabricated parts have been presented in detail. An overview of the mechanical properties of printed parts for different composite material systems is presented and discussed. Three types of reinforced polymers in FFF process have been considered: filled reinforced polymers, continuous fiber-reinforced polymers, and short fiber reinforced polymers.

Several natural materials and vegetable waste have relevant mechanical properties, mainly in its fiber format. Particularly, banana fiber (BF) provides a close behavior to the widely spread glass fibers, which places it in an advantageous position for use as a reinforcing material in plastic composites. This work characterizes the behavior of acrylonitrile butadiene styrene (ABS), high impact polystyrene (HIPS), and high density polyethylene (HDPE) reinforced with short fibers of bananas from the Canary Islands for its application in molding processes. Several thermal analyses (Thermal Gravimetric Analysis (TGA), Differential Scanning Calorimetry (DSC), and Melt Flow Index (MFI)) and mechanical tests (tensile, flexural, impact, and Dynamic Mechanical Analysis (DMA)) were carried out in composites with different percentages of banana fiber. The thermal results show that the use of banana fiber is viable as a reinforcement in composites for injection molding processes and the mechanical tests indicate an increase in stiffness and an improvement in maximum flexural stress by increasing the fiber content in composites, so the banana fiber turns out to be a natural alternative for the reinforcement of injected plastic components.

We describe an algorithm for generating fiber-filled volume elements for use in computational homogenization schemes. The algorithm permits to prescribe both a length distribution and a fiber-orientation tensor of second order, and composites with industrial filler fraction can be generated. Typically, for short-fiber composites, data on the fiber-length distribution and on the volume-weighted fiber-orientation tensor of second order is available. We consider a model where the fiber orientation and the fiber length distributions are independent, i.e., uncoupled. We discuss the use of closure approximations for this case and report on identifying the describing parameters of the frequently used Weibull distribution for modeling the fiber-length distribution. We discuss how to integrate these procedures in the Sequential Addition and Migration algorithm, developed for fibers of equal length, and work out algorithmic modifications accounting for possibly rather long fibers. We investigate the capabilities of the introduced methodology for industrial short-fiber composites, demonstrating the rather low dispersion of the effective elastic moduli for the generated unit cells.

Additive manufacturing is evolving in the direction of carbon fiber 3D printing, a technology that combines the versatility of three-dimensional printing with the exceptional properties of carbon fiber. This work aims to provide a brief review of the main methodologies used in carbon fiber 3D printing, focusing particularly on the two most widespread types: continuous fiber printing and short fiber printing. In the context of continuous fiber printing, the process of embedding a continuous carbon fiber into a polymer matrix will be examined, resulting in the achievement of high-performance lightweight structural components. On the other hand, short fiber printing involves the use of short carbon fibers mixed in turn with polymeric materials, with the advantage of having greater ease of processing and obtaining highly performing components with large-scale economic investments that are lower in cost than additive manufacturing using continuous fiber printing. Furthermore, this work will conduct an evaluation of the mechanical properties of products printed using both technologies, focusing on key aspects, such as strength, stiffness, weight, and resistance to mechanical stress. The specific advantages and challenges associated with each printing technique will also be analyzed.

HighlightsA multi-scale conductive network was constructed in flexible PDMS/Ag@PLASF/CNT composite with micro-size Ag@PLASF and nano-size CNT.The PDMS/Ag@PLASF/CNT composite showed outstanding electrical conductivity of 440 S m-1 and superior electromagnetic interference shielding effectiveness of up to 113 dB.The PDMS/Ag@PLASF/CNT composites owned good retention (> 90%) of electromagnetic interference shielding performance even after subjected to a simulated aging strategy or 10,000 bending-releasing cycles.Highly conductive polymer composites (CPCs) with excellent mechanical flexibility are ideal materials for designing excellent electromagnetic interference (EMI) shielding materials, which can be used for the electromagnetic interference protection of flexible electronic devices. It is extremely urgent to fabricate ultra-strong EMI shielding CPCs with efficient conductive networks. In this paper, a novel silver-plated polylactide short fiber (Ag@PLASF, AAF) was fabricated and was integrated with carbon nanotubes (CNT) to construct a multi-scale conductive network in polydimethylsiloxane (PDMS) matrix. The multi-scale conductive network endowed the flexible PDMS/AAF/CNT composite with excellent electrical conductivity of 440 S m−1 and ultra-strong EMI shielding effectiveness (EMI SE) of up to 113 dB, containing only 5.0 vol% of AAF and 3.0 vol% of CNT (11.1wt% conductive filler content). Due to its excellent flexibility, the composite still showed 94% and 90% retention rates of EMI SE even after subjected to a simulated aging strategy (60 °C for 7 days) and 10,000 bending-releasing cycles. This strategy provides an important guidance for designing excellent EMI shielding materials to protect the workspace, environment and sensitive circuits against radiation for flexible electronic devices.

Living cells and active factors are the two core elements of tissue repair, directly affecting the healing efficiency of damaged tissue. Nanofat (NF) can release living cells, such as adipose-derived stem cells (ADSCs), as well as active growth factors to promote angiogenesis, thus realizing cell-based wound healing. Herein, a novel living electrospun short fibrous sponge is constructed by modifying three-dimensional (3D) bionic short fibers with engineered NF. The uniform distribution of the polydopamine (PDA) modification endows the living sponges with stable mechanical properties, reversible water absorption and excellent adhesion even after repeated compression by an external force and long-term aqueous immersion. Meanwhile, the living electrospun short fibrous sponges with uniform NF modification contain living cells such as ADSCs and active growth factors such as vascular endothelial growth factor (VEGF), which can effectively promote the tube formation of human umbilical vein endothelial cells (HUVECs). In vivo , the living sponges can effectively and continuously act on wounds and act as a bionic living skin to prevent the loss of internal nutrients, creating a comfortable and favorable microenvironment for tissue regeneration and promoting the healing of diabetic wounds. Therefore, living electrospun short fibrous sponges via engineered NF are expected to achieve continuous wound healing with in situ living cells and active factors in injured tissues.

Human adenovirus 52 (HAdV-52) is one of only three known HAdVs equipped with both a long and a short fiber protein.While the long fiber binds to the coxsackie and adenovirus receptor, the function of the short fiber in the virus life cycle is poorly understood. Here, we show, by glycan microarray analysis and cellular studies, that the short fiber knob (SFK) of HAdV-52 recognizes long chains of α-2,8-linked polysialic acid (polySia), a large posttranslational modification of selected carrier proteins, and that HAdV-52 can use polySia as a receptor on target cells. X-ray crystallography, NMR, molecular dynamics simulation, and structure-guided mutagenesis of the SFK reveal that the nonreducing, terminal sialic acid of polySia engages the protein with direct contacts, and that specificity for polySia is achieved through subtle, transient electrostatic interactions with additional sialic acid residues. In this study, we present a previously unrecognized role for polySia as a cellular receptor for a human viral pathogen. Our detailed analysis of the determinants of specificity for this interaction has general implications for protein–carbohydrate interactions, particularly concerning highly charged glycan structures, and provides interesting dimensions on the biology and evolution of members of Human mastadenovirus G.

The main objective of this article is to develop ceramic-based materials for additive layer manufacturing (3D printing technology) that are suitable for civil engineering applications. This article is focused on fly ash-based fiber-reinforced geopolymer composites. It is based on experimental research, especially research comparing mechanical properties, such as compressive and flexural strength for designed compositions. The comparison includes various composites (short fiber-reinforced geopolymers and plain samples), different times of curing (investigation after 7 and 28 days), and two technologies of manufacturing (casted and injected samples—simulations of the 3D printing process). The geopolymer matrix is based on class F fly ash. The reinforcements were green tow flax and carbon fibers. The achieved results show that the mechanical properties of the new composites made by injection methods (simulations of 3D technology) are comparable with those of the traditional casting process. This article also discusses the influence of fiber on the mechanical properties of the composites. It shows that the addition of short fibers could have a similar influence on both of the technologies.

Sustainable hybrid composites, made of two different natural plant fiber types, are increasingly being attracted by composite researchers, for their cost effectiveness and ability to control mechanical performances through varying weight ratios of different fibers. In contrast, their lower mechanical properties are reported in the literature, because of strength variations of different fiber types and an improper fiber‐matrix stress distribution. Therefore, it is aimed to develop sustainable hybrid composites from two dry fiber preforms—woven fabric and short fiber preform—originated from same fiber type (jute). A highly packed short fiber preform is used as the core layer, while woven fabrics (plain/twill–rib/twill–diamond) are used in the skin layers for producing sandwiched hybrid jute composites. Mechanical tests and scanning electron microscopy images show that hybridized plain fabric/short fiber preform composites have better mechanical properties (≈58 MPa tensile strength/≈117 MPa flexural strength/≈112.12 kJm−2 impact strength with an ≈487.4% improvement) compared to other fabric structures hybrid/nonhybrid composites. This enhancement is related to the interlocking of short fibers with long plain fabric leading to a strong fiber‐matrix interfacial bonding. Thus, this developed hybrid composites, can be applied in many semi‐structural applications, wherein composites’ low cost and mechanical performances are primary concerns. Sustainable hybrid composites are developed using two different dry‐fiber preforms from the similar jute fiber type. Woven fabric and highly packed short jute fiber preform are used as skin and core layers respectively, in these sandwiched hybrid jute composites. Plain fabric/short fiber preform hybrid composites show improved mechanical properties. They are cost‐effective and can be used in semistructural composite applications.