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Nanostructured materials are difficult to prepare rapidly and at large scale. Melt-processed polymer-clay nanocomposites are an exception, but the clay content is typically below 5 wt%. An approach for manufacturing of microfibrillated cellulose (MFC)/kaolinite nanocomposites is here demonstrated in pilot-scale by continuous production of hybrid nanopaper structures with thickness of around 100 μm. The colloidal nature of MFC suspensions disintegrated from chemical wood fiber pulp offers the possibility to add kaolinite clay platelet particles of nanoscale thickness. For initial lab scale optimization purposes, nanocomposite processing (dewatering, small particle retention etc) and characterization (mechanical properties, density etc) were investigated using a sheet former (Rapid Köthen). This was followed by a continuous fabrication of composite paper structures using a pilot-scale web former. Nanocomposite morphology was assessed by scanning electron microscopy (SEM). Mechanical properties were measured in uniaxial tension. The fire retardancy was evaluated by cone calorimetry. Inorganic hybrid composites with high content of in-plane oriented nanocellulose, nanoclay and wood fibers were successfully produced at pilot scale. Potential applications include fire retardant paperboard for semi structural applications and as reinforcement mats in molded thermoset biocomposites. [ABSTRACT FROM AUTHOR]

This study investigated mechanical properties of biocomposites developed from recycled polylactic acid (PLA) from packaging industry and treated cellulosic fibers from pulp and paper solid waste. Microwave and enzymatic treatments were used for extraction and surface modification of hydrophilic cellulosic fibers. Enzymatic treatment was specifically performed for activation of hydroxyl groups and improvement of adhesion between matrix and fibers including controlling the length of cellulosic fibers with size reduction of around 50% (142 and 127 μm for primary and mixed biosolids, respectively) as compared to microwave treatment. Microwave treatment produced cellulosic fibers of 293 and 341 μm, for primary and mixed biosolids, respectively. Mechanical properties of biocomposites with 2% (w/w) of treated cellulosic fibers (Young's Modulus 887.83 MPa with tensile strain at breakpoint of 7.22%, tensile stress at yield 41.35 MPa) was enhanced in comparison to the recycled PLA (Young's Modulus 644.47 ± 30.086 MPa with tensile strain at breakpoint of 6.01 ± 0.83%, tensile stress at yield of 29.49 ± 3.64 MPa). Scanning electron microscopy revealed size reduction of cellulosic fibers. X-ray diffraction and Fourier transform infrared spectroscopy confirmed strong mechanical properties of novel biocomposites. [ABSTRACT FROM AUTHOR]

• The theory of shear lag model is extended. • Viscoelastic shear lag model is developed to illustrate the mechanical behavior of axon under transient tensile loading. • The paper explains how the vulnerable axons protect themselves from overall damage over the course of evolution. • The paper explains how axons achieve an outstanding mechanical balance of high stiffness and toughness. Axons with staggered microtubules cross-linked by tau protein possess a remarkable mechanical balance of high specific stiffness and toughness. Owing to their viscoelastic nature, axons exhibit stress rate-dependent mechanical behavior, which is relevant to their selective vulnerability to damage in traumatic brain injury. A Kelvin–Voigt viscoelastic shear lag model is developed to elucidate the mechanical responses of axons under transient tensile force. Analytical closed-form expressions are derived to characterize the relative sliding, stress transfer and failure mechanism between microtubule and tau protein while the axon is stretched transiently. The results from the theoretical solutions elucidate how the MT-tau interface length and stress rate affect the mechanical responses of axon. It is found that axonal failure mechanism may be different under different loading conditions. Long microtubules are more vulnerable to rupture at high stress rate, yet short microtubules are likely to detach from microtubule bundles under large deformations. In the view of multi-level failure of axon, it is illustrated how the vulnerable axons protect themselves from overall damage, and how the axon can simultaneously achieve an outstanding mechanical balance of high specific stiffness and toughness. [ABSTRACT FROM AUTHOR]

Abstract A new approach to manufacture biocomposite sandwich structure is introduced with all materials naturally derived, including jute, flax and cellulose textile as reinforcement skin; mycelium-bound agricultural waste as lightweight cores; and a soy-based bioresin as a matrix. This new material could be used to replace many of the plastic products that are widely used today and therefore preventing the production of waste, while increasing efficiencies in the use of nonrenewable resources. This paper focuses on the final step of the seven-step manufacturing process: resin infusion followed by curing in place for the grown then deactivated mycelium sandwich beams. Specific process details that are highlighted include designing and building the preliminary transparent resin transfer molding for resin flow behavior study, design and fabrication of the aluminum permanent mold prototype, three-point bending flexural tests of the resin infused then cured sandwich beams to determine their strengths, and finally, finite element simulation using Abaqus software to simulate the three-point bending process. To obtain the skin reinforcements' Young's and shear moduli, tensile and V-groove shear tests were performed based on corresponding ASTM standards. It is concluded that although the skin material is the one that carries most of the loads, the strength of the sandwich structure appears to largely depend on the degree of fungal colonization within the core and bonding between the skin and core. The cured resin increased the beams' core shear ultimate stress, core shear yield stress, skin ultimate stress and flexural strengths of the sandwich beams by factors of 1.5–6.5, and the finite element simulation results agreed with the actual situations, which well explained the beams' most common failure mode in flexural bending. [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]

A new technique based on tube shrinkage is proposed for the fabrication of composite archwires. Compared with a traditional pultrusion method, this new technique can avoid any fiber damage during the fabrication and can provide the archwire with a required curvature in its final clinical usage. The present paper focuses on the technique development and mechanical design and validation in terms of constituent materials by using a micromechanics bridging model. Prototype archwire has been fabricated using fiberglass and an epoxy matrix, with a wire diameter of 0.5 mm and a 45% fiber volume fraction. Tensile and three-point bending tests have shown that the mechanical performance of the prototype composite archwire is comparable to that of a clinical Ni–Ti archwire. Another purpose of the present paper is to provide an efficient procedure for a critical design of composite archwires. For this to be possible, the ultimate load especially flexural load carrying ability of the composite archwire must be assessed from the knowledge of its constituent properties. However, difficulty exists in doing this, which comes from the fact that the failure of the utmost filament of the composite archwire subjected to initially the maximum bending stress does not imply its ultimate failure. Additional higher loads can still be applied and a progressive failure process is generated. In this paper, the circular archwire was discretized into a number of parallel laminae along its axis direction, and the bridging micromechanics model combined with the classical lamination theory has been applied to understand the progressive failure process with reasonable accuracy. Only the constituent fiber and matrix properties are required for this understanding. Nevertheless, the ultimate bending strength cannot be obtained only based on a stress failure criterion. This is because neither the first-ply nor the last-ply failure corresponds to the ultimate failure. An additional critical deflection (curvature) condition must be employed also. By using both the stress failure and the critical deflection conditions, the predicted load-deflection up to the ultimate failure agrees well with the measured data. Thereafter, different mechanical performances of composite archwires can be tailored before fabrication by choosing suitable constituent materials, their contents, and the archwire diameters. Several design examples have been shown in the paper. [Copyright &y& Elsevier]

[Display omitted] • A novel inverse biological crossed-lamellar structure was synthesized in CFRP. • This is the first non-biological prototype crossed-lamellar structure in the literature. • The tailored inverse-biologic crossed-lamellar structure is designed to achieve higher load-carrying capacity and stiffness. The remarkable toughness of Strombus gigas shell arises from its microstructure. In this study, inspired by the biologic crossed-lamellar microstructure of Strombus gigas shell, we prepared a novel carbon fiber reinforced polymer (CFRP) composite with inverse-biologic crossed-lamellar structure by replacing the inner and outer layers with the "tough" middle structure. The influences of the alternating arrangement of crossed-lamellar three-layer structure on the mechanical responses, including toughening mechanisms and biological mechanism, were studied. Experimental and numerical results indicated that as burrowing mollusks, Strombus gigas shells require a balance of certain load-carrying capacity and stronger protection function. Meanwhile, the tailored inverse-biologic structure achieved higher load-bearing capacity and stiffness. Additionally, the Bouligand-ply design strategy was proposed as an alternative to the traditional angle-ply design for the crossed-lamellar structure. By changing the laying-up form and pitch angle of the middle layer, a significant improvement in both load-bearing and energy dissipation capacity of the structures was achieved. The paper provides valuable insights for the design of high-performance biomimetic crossed-lamellar structures and holds great potential for the customization of fiber-reinforced composites. [ABSTRACT FROM AUTHOR]

State-of-the-art workflows within Architecture, Engineering, and Construction (AEC) are still caught in sequential planning processes. Digital design tools in this domain often lack proper communication between different stages of design and relevant domain knowledge. Furthermore, decisions made in the early stages of design, where sketching is used to initiate, develop, and communicate ideas, heavily impact later stages, resulting in the need for rapid feedback to the architectural designer so they can proceed with adequate knowledge about design implications. Accordingly, this paper presents research on a novel integrative design framework based on a recently developed 4D sketching interface, targeted for architectural design as a form-finding tool coupled with three modules: (1) a Geometric Modelling module, which utilises Points2Surf as a machine learning model for automatic surface mesh reconstruction from the point clouds produced by sketches, (2) a Material Modelling module, which predicts the mechanical properties of biocomposites based on multiscale micromechanics homogenisation techniques, and (3) a Structural Analysis module, which assesses the mechanical performance of the meshed structure on the basis of the predicted material properties using finite element simulations. The proposed framework is a step towards using material-informed design already in the early stages of design. [ABSTRACT FROM AUTHOR]

Aligning the sustainability in construction process can be achieved through material selection process with low impact on environment and human health. Today, biocomposite materials are investigated and developed to replace with none, and less eco-friendly materials used in the construction industry leading to emergence of next generation of sustainable and green building materials. This paper aims to develop a model of fully hybrid bio-based biocomposite based on Life Cycle Assessment (LCA), and comparing it with fully petroleum-based composite, which are common conventional building materials. The methodology framework of this research is determined based on ISO 14040 and 14044. Also, the ReCiPe as the common method in SimaPro software is chosen for appraising and comparing LC impact assessment (LCIA). This research highlights the negative effect of these kinds of building materials with providing single scores coming from three gauges including Human Health, Ecosystems and resources. It is observed that substituting the biocomposite with the fully petroleum-based composite has led to a decline of about 30% in single score outcome. The significance of this research is related to important judgement information to policy makers and the prospective manufacturers in the commercialization phase of this new biocomposites as sustainable and green building materials. [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]

In this paper, analytical and 3D numerical models are developed to investigate the mechanical behavior of sandwich pipe under internal pressure loading. The suggested models provide an exact solution for stresses, strains and displacement on the sandwich pipe, which is made of epoxy material for the core layer and reinforced materials with an alternate-ply for the skin layers. The aim of this analysis is to evaluate the potential applications of jute and pineapple leaf fiber (PALF) bio-fibers in order to replace glass synthetic fibers generally employed in sandwich pipes. In this subject, a failure analytical analysis was developed using TSAI-WU criterion. The results of stress, strain and displacement distribution through the thickness are presented for the analytical and numerical models. The comparison between the both models results show a very good agreement. In order to increase the rigidity of a biocomposite sandwich and reduce the gap compared with a synthetic sandwich, a gradual reinforcing of layer numbers was chosen, which permitted the best behavior. The ultimate pressure and safety factors obtained by increasing biocomposite layers are significant for composite transportation pressure pipelines, especially for sandwich pipe based on PALF/epoxy. • We aim at modeling a sandwich pipe under internal pressure loading using analytical and 3D numerical models for failure analysis. • The structure is a made of epoxy material for the core layer and reinforced materials with an alternate-ply for the skin layers. • Evaluate the potential applications of bio-fibers in order to replace synthetic fibers generally employed in sandwich pipes using TSAI-WU criterion. • Substituting synthetic fibers by bio-fibers yields a satisfactory result by increasing the number of layers. [ABSTRACT FROM AUTHOR]

• A better and diversified technological use of by-products from the pulping industry. • Innovative hydrothermal phenolic resin from a blend of crude Kraft black liquor and tannin. • Thermal treatment was performed in the hydrothermal phenolic resin to obtain its carbon counterparts. • The thermal treatment increased the adsorbents basicity, which was confirmed through FTIR and pH PCZ studies. • The newly synthesized materials can be applied as a low-cost adsorbent for paracetamol and aspirin removal. An alternative use for the Kraft Black liquor, the main byproduct of the pulping process, is presented in this work. It is a promising route for new biorenewable materials production, reducing dependence on petrochemicals. The synthesis of the novel biobased composites from a blend of tannin and Kraft black liquor involved a polycondensation reaction followed by a crosslinking process. This paper is the first one emphasizing the synthesis of a novel biobased composite from a blend of Kraft black liquor and tannin by performing the conventional and hydrothermal crosslinking. The hydrothermal conditions proved to be an effective strategy to obtain an oxygen-rich functional material. Besides being environmental-friendly, the hydrothermal process successfully replaced conventional curing, providing a higher yield and better chemical, functional, and structural properties. The role of two different processes, hydrothermal and pyrolysis, on the properties and adsorption performance of the final composites, was also assessed. RFA was obtained by hydrothermal conversion, processed at relatively mild conditions when compared to the pyrolysis performed to produce its carbon counterpart, RFC. Pyrolysis promoted a mesoporous structure on the RFC and the textural properties were improved. On the other hand, the severe thermal treatment degraded the RFC functional groups, increasing its basicity and decreasing the number of polar groups on the surface. RFA exhibited a smaller surface area than RFC, but it retained volatile organic matter and functional oxygen groups. These surface characteristics are known to be relevant in adsorption processes since the adsorbate-adsorbent chemical linkages and electrostatic interactions are favored. Paracetamol and aspirin adsorption onto RFA achieved the equilibrium at 480 and 720 min. On the other hand, the equilibrium for the adsorption onto RFC was achieved at 720 and 240 min. The maximum aspirin adsorption capacities onto RFA and RFC were 50.17 mg g−1 and 91.66 mg g−1, respectively. On the other hand, for paracetamol, the maximum adsorption capacities were 49.95 mg g−1 onto RFA and 73.58 mg g−1 onto RFC. The kinetic study suggested fast adsorption through a chemisorption process and the equilibrium implies the multilayer adsorption. Additionally, the major advantages of using the raw Kraft black liquor blended with tannin to synthesize the novel composites are their great availability and low cost, enabling the material large-scale production. Therefore, the results confirm the great potential of these new biomaterials as alternative adsorbents for wastewater treatment. [ABSTRACT FROM AUTHOR]

Composite materials based on renewable agricultural and biomass feedstocks are increasingly utilized as these products significantly offset the use of fossil fuels and reduce greenhouse gas emissions in comparison with conventional petroleum-based materials. However, the inclusion of natural fibers in polymers introduces several challenges, such as excess water absorption and poor thermal properties, which need to be overcome to produce materials with comparable properties to the conventional composite materials. Instead of using rather expensive chemical and physical modification methods to eliminate these aforementioned challenges, a new trend of utilizing waste, residues, and process by-products in natural fiber-polymer composites (NFPCs) as additives or reinforcements may bring considerable enhancements in the properties of NFPCs in a sustainable and resilient manner. In this paper, the effects of waste materials, residues or process by-products of multiple types on NFPCs are critically reviewed and their potential as NFPC constituents is evaluated. [ABSTRACT FROM AUTHOR]

Abstract: Natural fibers have recently become attractive to researchers, engineers and scientists as an alternative reinforcement for fiber reinforced polymer composites. This paper is focused on the tensile properties of natural fiber reinforced polylactic acid composites. The untreated and flexible epoxy treated bamboo fiber, vetiver grass fiber and coconut fiber were used as reinforcement for PLA biocomposites. The stiffness of untreated biocomposites increased significantly with increasing of fiber content. However, the tensile strength decreased with increasing of fiber content. The flexible epoxy surface treatment reduced the stiffness of all composites while it considerably increased tensile strength when compared against the untreated composites. In addition, it can be seen that the effects of flexible epoxy treated on the tensile strength improvement were dependent upon the type of natural fiber. The tensile strength of bamboo fiber and coconut fiber reinforced PLA composites were significantly improved by the flexible epoxy surface treatment. Unlike the other combinations, vetiver grass fiber reinforced PLA composite showed less improvement in tensile strength when comparing with other natural fibers. Bamboo fiber proved to be the most effective reinforcement compared to other reinforcements. [Copyright &y& Elsevier]

Abstract: Over the last few years, intensive research has been devoted to the exploitation of “green products” based on natural resources for both matrices and as reinforcements in composite systems. The mechanical properties of reinforced biocomposites, such as flax/polylactic acid (PLA), are largely governed by interfacial properties between the two constituents apart from their intrinsic properties. Although many papers indirectly demonstrate the importance of optimising the interface between these two polymers, the exact nature of the interaction between the natural fibre and the polymeric matrix has not been clearly investigated on a fundamental level and is presently a major technological limitation of these materials. This work presents the first direct study of adhesion forces, by colloidal force microscopy, between smooth PLA films representing the polymer matrix, and a microbead of cellulose that mimic the cellulose material in flax fibres. Normalised adhesion force measurements have shown the importance of capillary forces when experiments were carried out under ambient conditions. Experiments, conducted under dry air, allowed for the deduction of the contribution of pure van der Waals forces, and our results, through the calculation of the Hamaker constant, show that these forces, for the PLA/cellulose/air system, were lower than those obtained for the cellulose/cellulose/air system and hence underlined the importance of optimising the interface among these materials. This study demonstrates the capacity of AFM to probe direct interactions in complex systems by adjusting the nature of the surface and the probe to mimic the materials in contact. Furthermore, the technique can be operated in a variety of environments, consistent with composite making and provides particular opportunity for testing and improving the properties of these new classes of composite materials. [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]

This paper presents and analyzes the behavior of bumper beams made of PLA/flax composites subjected to low velocity impacts. The relevance of this material resides in the biodegradability of both fibers and matrix. Moreover, the after-impact behavior of this composite is excellent due to the absence of delamination. Impact tests have been performed using a drop weight tower within the range of impact energies 5 J ≤ E imp ≤ 73 J. The experimental setup enabled the measuring of impact velocity, residual velocity, load-time history and failure mode. Results show that damage generated during impact produces a significant reduction of residual stiffness but the residual strength is not affected by damage generated in the range of the applied impact energies considered. [ABSTRACT FROM AUTHOR]

• The effect of open-hole on mechanical properties of flax laminates was investigated. • Strain field around hole was analysed using Digital image correlation. • Acoustic emission was used to monitor the progressive damage during tensile testing. • Acoustic events were classified to calculate the contribution of each damage modes. • SEM pictures were used to visually identify the damage mechanisms. The present paper is dedicated to the assessment of the damage taking place in open-hole flax bio-epoxy laminates with different stacking sequences. Tensile test results have shown significant effects of the open hole on the performance of the laminate. Moreover, strain maps have allowed to detect the onset of cracks and to discuss their contribution to the laminates failure. For unidirectional laminate, splitting was observed as the main damage at the hole boundary along the fiber orientation and parallel to the loading axis. However, the [0 90] 6s laminate failure has caused by the onset of subsurface cracks in the 90° plies. Even if the tensile strength was decreased, the strain fields result has shown a less hole sensitive behavior of the [0 +45 90 −45] 3s laminate. Finally, damage monitoring using acoustic emission has shown a significant increase of the fiber-matrix debonding and fiber breakage contribution to the laminate failure. [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]