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Wood plastic composite (WPC) is a kind of eco‐friendly material made of agricultural and forest industry waste and residues compounded with thermoplastic. The defects of traditional WPC, such as low strength and high creep, greatly limit its engineering applications. To solve the problem, this paper proposed two methods of glass fiber reinforced polymer (GFRP) reinforced PVC‐based WPC panels (G‐WPC) by bonding GFRP sheets or embedding GFRP bars in the tensile zone of the WPC panels. The effects of the thickness of GFRP sheet and reinforcement ratio of GFRP bar on the flexural property of G‐WPC were comparatively analyzed by carrying out four‐point bending tests and finite element simulations. The results showed that the failure modes of the GFRP sheets reinforced specimens were mainly flexural fracture and interface debonding, and the GFRP bars reinforced specimens were flexural fracture and excessive deformation. The ultimate flexural bearing capacity of both GFRP sheets/bars reinforced specimens could be improved by more than 200%. GFRP bar reinforced specimens had better ductility than reinforced with sheet. The effects of WPC density, GFRP sheet fiber layup angle and GFRP bar diameter on the flexural behavior of G‐WPC were further parametrically analyzed using the finite element model (FEM). Highlights: Two effective flexural reinforcement methods of WPC were proposed.The optimum thickness of GFRP sheet was obtained based on experimental tests.The suitable reinforcement ratio of GFRP bars was studied by tests and FEM.Effects of WPC density, GFRP fiber layup angle and bar diameter were analyzed. [ABSTRACT FROM AUTHOR]

The steel-wood composite beam with I-section is made of laminated veneer lumber (LVL) and cold-formed thin-wall steel by structural adhesive. The flexural properties of nine composite beams are tested with parameters such as LVL plate thickness, section height, thin wall steel thickness and flange LVL width. The failure forms, deflection development, strain distribution and bearing capacity of specimen are observed, the influence factors of flexural property are analyzed, and a formula for calculating midspan deflection considering the slip effect is proposed. The results show that steel-LVL composite beams have good overall working performance. The composite beam has a high deformation ability before failure, and the most typical failure mode is the lower flange LVL fracture. The material properties are fully utilized, showing good ductility. The flexural bearing capacity of composite beams can be improved by increasing the ratio of section height to width and web height to thickness and reducing the ratio of flange width to thick‐ ness. The slip between the LVL and the section steel reduces the stiffness of the composite beam. Compared with the results without taking slip into account, the theoretical calculation results of mid-span deflection of composite beam with interface slip effect are closer to the real deformation, and the calculation accuracy is improved by 2. 38%. [ABSTRACT FROM AUTHOR]

Carbon fiber‐reinforced composite materials exhibit excellent mechanical and electromagnetic shielding capabilities. However, they have some drawbacks, such as high cost and significant reflection losses. In order to address these shortcomings, this study set out to design a sandwich‐structured composite material and produce a composite material designed for electromagnetic shielding using Vacuum Assisted Resin Transfer Molding (VARTM) technology. This composite material promotes the "absorption‐reflection‐reabsorption" process of electromagnetic waves, significantly enhancing its shielding effectiveness, achieving up to 59.4 dB of shielding effect in the 8.2–12.4 GHz (X‐band) range. The study also employed carbon nanotubes (CNTs) matrix doping to modify the composite material, significantly reducing reflection losses. When the amount of carbon nanotubes added reaches 0.6 wt%, the overall SE can be increased by 18%. Additionally, the introduction of CNTs significantly improves the flexural strength and tensile strength of the composite material; at a 0.6 wt% CNT content, the average tensile strength increased from 526.4 to 600.9 MPa, indicating good interfacial interactions between CNTs and epoxy resin. This work provides valuable insights for the preparation of high‐performance electromagnetic shielding materials, with profound theoretical and practical significance. Highlights: Observations through SEM and CT scanning techniques reveal that Vacuum Assisted Resin Transfer Molding (VARTM) technology facilitates strong interlayer bonding between carbon fibers, glass fibers, and copper wires, alongside effective epoxy resin adhesion, thus enhancing the mechanical properties.The sandwich structure's impedance mismatch characteristic facilitates an efficient "absorption‐reflection‐reabsorption" process of electromagnetic waves. Additionally, the incorporation of Carbon Nanotubes (CNTs) enhances the absorption mechanism, reducing reflection losses.Incorporating CNTs further boosts both flexural and tensile strengths, attributed to improved interfacial interactions inhibiting crack formation. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Materials Engineering / Cailiao Gongcheng is the property of Journal of Materials Engineering Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

C/C-SiC composites were prepared by chemical vapor infiltration （CVI） and reactive melt infiltration （RMI） using carbon fiber preforms with stitched and needle-punched structures. The microstructure and pore characteristics of C/C porous composites obtained from the two structural preforms， as well as the microstructure and flexural properties of C/C-SiC composites， were systematically studied. Results show that the pore size of stitched C/C porous composite is multimodal distribution， and the pores are mostly inter-bundle pores. The pore size of needle-punched C/C porous composite is unimodal distribution. Due to the addition of mesh， some inter-bundle pores are transformed into connected small pore networks. The simulated absolute permeability in the Z direction of the latter is slightly greater than that of the former， which is conducive to the subsequent RMI densification process of the latter （high density， low open-porosity and low residual metal）. The average flexural strength of stitched C/C-SiC composites is higher than that of needle-punched C/C-SiC composites， both of which exhibit a “pseudo plastic” fracture mode. The needle-punched C/C-SiC composite has a higher density and lower residual Si content， but its fiber volume content is lower， and the integrity of long straight fibers is poor， resulting in lower load-bearing property of the composite.

In the current work, the strength and elastic properties of MXene/CNT reinforced epoxy/glass fibre based nanocomposites were investigated using experimental and analytical approach. To achieve this, the Halpin-Tsai model and Chamis model was employed to evaluate the mechanical properties of two -phase (MXene-CNT)/Epoxy composite and three-phase (MXene-CNT)/Epoxy/Glass fibre composite. The accuracy of the analytical model was verified by comparing the results with the experimental data. To study the strength properties of the composites in detail, experimental tensile and flexural tests were carried out. Finally, a parametric study was performed to investigate the influence of weight fractions and aspect ratios on the elastic properties of MXene/CNT reinforced composites. It was observed that the MXene/CNT reinforced glass/epoxy based composite exhibited higher load bearing capacity as compared to neat glass/epoxy composite for all the performed mechanical tests. The tensile, shear and flexural modulus of MXene/CNT reinforced laminated composite were found to be 17.2%, 15.6%, and 16.2%, higher in comparison to the neat glass/epoxy laminated composite. The addition of nano-fillers exerted positive impact on the elastic properties of both the two-phase and three-phase nanocomposites and the properties kept on improving with weight fraction of the nano-fillers. Regarding the impact of aspect ratio on elastic modulus, however, conflicting findings were noted. Increase in the aspect ratio, on one hand, resulted in an increase in the longitudinal elastic modulus; on the other hand, it resulted in a monotonous reduction in the shear modulus.

Carbon fiber reinforced plastic (CFRP) composites have been widely used in engineering. This paper investigates the effect of composite z-pin (polyimide fiber/epoxy resin) on flexural properties of skin/stringer composite structure with different z-pin densities and diameters. Compared with unpinned specimens, the peak loading and energy absorption of z-pinned specimens are increased by 98% and 9 times, respectively. Parameterized research indicates that the optimal z-pin density is 1.35%. And thin z-pins are beneficial to improve the peak loading and energy absorption, which attributes to more total contact area of z-pins. The statistical results present that z-pin pre-hole inserted (ZPI) process can significantly reduce initial damages of z-pinned specimens compared with Ultrasonically Assisted Z-fiber (UAZ) process. Specifically, the z-pin inclination angle is decreased by 60%, and the initial damages in eye-like zone are prominently reduced. The z-pin makes the specimen exhibit the quasi-brittle behavior under flexural loading by playing a bridging role, which makes the flexural properties of specimens prominently increased. In addition, the "snubbing effect" will enhance the bridging effect of z-pins, but it will lead to inter-fibers debonding, splitting, and shear failure of z-pins. [ABSTRACT FROM AUTHOR]

The exploration of unleaded free-cutting Cu40Zn brass with excellent mechanical and tribological properties has always drawn the attention of researchers. Due to its attractive properties combining metals and ceramics, Ti3AlC2 was added to Cu40Zn brass using high-energy milling and hot-pressing sintering. The effects of Ti3AlC2 on the microstructure, mechanical and tribological properties of Cu40Zn-Ti3AlC2 composites were studied. The results showed that Ti3AlC2 could suppress the formation of ZnO by adsorbing oxygen impurity and promote the formation of the β phase by releasing the β-forming element Al to the substrate. The hardness and wear resistance of Cu40Zn-Ti3AlC2 composites increased with increasing Ti3AlC2 content from 0 to 5 wt.%. The proper Ti3AlC2 additive was beneficial to both the strength and plasticity of the composites. The underlying mechanisms were discussed. [ABSTRACT FROM AUTHOR]

To address the issue of pavement cracking due to brittle concrete in road and bridge engineering, this study explores the use of high–ductility magnesium phosphate cementitious concrete (HD–MPCC) for rapid repairs. The deformation and frost properties of HD–MPCC are analyzed to assess its suitability for this application. Deformation properties were tested for HD–MPCC specimens cured in both air and water. Subsequent tests focused on the frost performance and mechanical properties after freeze–thaw cycles. A mercury penetration technique was utilized to examine the pore structure. The findings reveal that the expansion deformation of HD–MPCC increases with curing age in both air and water conditions, and the quantitative relationship between the expansion deformation and curing age of HD–MPCC was analyzed. Additionally, the freeze–thaw cycles led to a decrease in mass loss, the relative dynamic elastic modulus, the ultimate tensile strength, the ultimate tensile strain, the flexural strength, and the peak deflection. The volume fraction of harmless and less harmful pores gradually decreased as the freeze–thaw cycle increased, while the volume fraction of more harmful pores increased, resulting in a decrease in the strength, ultimate tensile strain, and peak deflection. [ABSTRACT FROM AUTHOR]

Copyright of Cotton Textile Technology is the property of Cotton Textile Technology Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

An underground grain silo with assembled steel plate-concrete composite is characterized by land and energy saving, carbon reduction, green environmental protection, airtight and low temperature. The connection joint is one of the most critical parts of the assembled structure. Structural form and mechanical properties have restricted the development, popularization, and application of underground assembled composite structures. All-welded joints are currently used in underground silos, leading to the weld challenging with numerous weld seams. In this study, a type of bolt-weld vertical joint was proposed for the assembled composite underground silo with steel plate-concrete composite. The bolts were also used to replace the portion of the weld. The length of the weld was then reduced to easily position the members. Both bolts and welds were used to connect the assembled parts of concrete, internal steel plate, external waterproof steel plate, and internal waterproof steel plate. Two specimens of bolt-weld vertical joints were designed: A single-sided three- and five-bolt specimen. Two-point symmetric loading tests were carried out to determine the bending performance of steel plate-concrete composite plates. A systematic analysis was made of the failure pattern and bearing capacity of specimens. The results indicate that the single-sided three- and five-bolt specimens shared similar bearing capacities of 1 998 and 2 053 kN, respectively. The load-displacement curves showed that the single-sided five-bolt specimen was much more susceptible to the brittle damage, whereas, the single-sided three-bolt specimen exhibited better ductility after failure. Therefore, a three-bolt joint was recommended to design the joint in a practical project. A finite element model of assembled underground grain silo joint was then established to derive the bearing capacity. The relative error of the overall average on deflection finite element and test strain for SC-3 was 4.17%, indicating agreement with the excellent numerical and experimental one. A parameter study was conducted to establish finite element models with various design variables. A systematic investigation was made to clarify the influence of concrete strength, the thickness of internal waterproof steel plate, external waterproof steel plate, and internal steel plate on the ultimate bearing capacity and peak displacement of the structure. The regression coefficients of concrete strength, internal waterproof steel plate thickness, external waterproof steel plate thickness, and internal steel plate thickness to peak load were 0.993, -0.003, -0.012, and 0.056, respectively. The bending bearing capacity of the joint depended significantly on the strength of the concrete, while there was little effect on the thickness of the steel plate. The increasing concrete strength more effectively improved the bearing capacity of the joint in the practical project. The higher concrete strength may result in the low ductility of the specimen. Therefore, it is recommended to select the optimal concrete strength. This finding can provide reliable scientific information to design the connection joint of the assembled composite underground silo with steel plate-concrete. [ABSTRACT FROM AUTHOR]

Carbon fiber composite fan blade (CFCFB) is gradually applied to aerospace because it possesses less density and high strength than metal materials. However, the flexural property of conventional CFCFB is generally limited due to centrifugal and aerodynamic flexural stresses. Herein, a bionic gradient double-twisted structure (BGDTS), which was composed of different modulus carbon fiber prepreg gradient structure (inspired by metopograpsus frontalis cheliped tip) and double-twisted (inspired by coelacanth scale) layup structure was designed. Besides, the flexural properties of laminates with different structures and materials were tested, and the 3D Hashin failure criterion was used for simulation analysis. The experimental and simulation results showed that bionic gradient double-twisted structure laminate (BGDTSL) had the best flexural performance (peak flexural force 1125.12 N). Then, the excellent moulding accuracy of CFCFB was verified by the three-dimensional scanning test (moulding accuracy less than 0.56 mm). Among, the tip, middle, and root peak flexural force of the BGDTS-CFCFB were 7022 N, 3327 N, and 5184 N, which increased by 9.27%, 4.59%, and 14.31% compared with traditional structure CFCFB prepared by T800 (TS-CFCFB@T800). The researches in this work offer a prospective way to effectually devise and manufacture exquisitely structured CFCFBs that are more suitable for aeronautical engineering.

The exploration of unleaded free-cutting Cu40Zn brass with excellent mechanical and tribological properties has always drawn the attention of researchers. Due to its attractive properties combining metals and ceramics, Ti3AlC2 was added to Cu40Zn brass using high-energy milling and hot-pressing sintering. The effects of Ti3AlC2 on the microstructure, mechanical and tribological properties of Cu40Zn-Ti3AlC2 composites were studied. The results showed that Ti3AlC2 could suppress the formation of ZnO by adsorbing oxygen impurity and promote the formation of the β phase by releasing the β-forming element Al to the substrate. The hardness and wear resistance of Cu40Zn-Ti3AlC2 composites increased with increasing Ti3AlC2 content from 0 to 5 wt.%. The proper Ti3AlC2 additive was beneficial to both the strength and plasticity of the composites. The underlying mechanisms were discussed.

Based on the self-made Zr0.5Hf0.5C precursor and commercial liquid polycarbosilane, C/Zr0.5Hf0.5C-SiC composite was successfully prepared by the precursor impregnation and pyrolysis(PIP) process. The influence of the thickness of pyrolytic C coating on the structure and bending properties of composite materials was studied. The results show that the self-made Zr0.5Hf0.5C precursor can be converted into Zr0.5Hf0.5C solid solution at a relatively low temperature of 1400 ℃. Because of its good permeability, the transformed Zr0.5Hf0.5C matrix exists in both the inter-bundle and intra-bundle regions of the C/Zr0.5Hf0.5C-SiC composite, which presents as a layered structure on SiC matrix. The phase composition of C/Zr0.5Hf0.5C-SiC composite mainly includes C, SiC and Zr0.5Hf0.5C. The densities of three groups of composites with different thicknesses of pyrolytic C coating (0.67, 0.84, 1.36 μm) are 2.07, 1.99, 1.98 g/cm3, respectively. SiC content in the composite decreases with the increase of the thickness of pyrolytic C coating. The three groups of composites with different thicknesses show pseudoplastic fracture mode during bending loading tests, bending strength, bending modulus and fracture toughness are above 410 MPa, 60 GPa and 15.6 MPa·m1/2, respectively. Good interface bonding and pre-introduced SiC matrix are the keys to obtaining excellent bending properties of C/Zr0.5Hf0.5C-SiC composites.

The general two-dimensional (2D) woven laminated composite (GWLC) is widely used in aviation, aerospace and high speed railways, and its superior specific stiffness and strength substantially reduce the weight of the structural components. However, when the GWLC is damaged by flexural, shear and impact loads, the layers are prone to delamination. To improve the interlayer properties of the GWLC, a loop warp yarn is added to the plain fabric by means of three-dimensional (3D) weaving technology, resulting in a double-side-loop fabric with Z-directional fibers. This paper investigates the double-notched shear (DNS) properties, in-plane shear properties, and flexural properties of GWLC and a new double-side-loop 2D woven laminated composite (DWLC). The test results verify that adding the loop warp yarns can greatly improve the interlayer properties of the general 2D woven laminated composites. The DWLC increases the interlaminar shear strength by 81.5%, the in-plane shear strength by 49.4%, and the flexural strength and modulus by 90.2% and 61.4%, respectively. The excellent mechanical properties of the DWLC lay a foundation for loop fabrics in engineering applications. [ABSTRACT FROM AUTHOR]

AbstractThe current study focuses on the investigation of the synergetic effect of graphene nanoplatelets (GNPs) and carbon nanotubes (CNTs) on the flexural properties, hardness and water absorption characteristics of glass fiber reinforced polymer (GFRP) laminated composite materials. The laminated composite materials were fabricated with various configuration of filler reinforcements using vacuum assisted hand lay-up technique. Further, micromechanical analysis was performed using Halpin-Tsai model to investigate the synergistic effect of CNT/GNP hybrid glass fiber reinforced epoxy nanocomposites. It was observed that the CNT and GNP reinforced hybrid composite exhibited highest value of flexural strength and hardness; the respective values being 38% and 29% higher in comparison to the neat epoxy composite. Furthermore, among GNP and CNT, the composite containing former reinforcement exhibited better mechanical properties. The composites containing nanoparticles also exhibited better water uptake characteristic, where the weight gain for hybrid composite was 1.004%, whereas, for neat epoxy composite, the weight gain was 1.210%. This was attributed to the ability of nanofillers to restrict the intermolecular movement of the surrounding GFRP composites, which delays the relaxation of polymer chains, thereby reducing the diffusion of tiny molecules through the composites. It was also observed that the addition of GNPs has a strong effect on the elastic properties of the hybrid glass fiber reinforced epoxy nanocomposite than the addition of CNTs.

Fiber reinforced polymer (FRP) bars have been widely used as a replacement for steel bars in civil engineering due to their high strength and superior durability. However, compared to steel reinforced concrete (RC) beams, FRP RC beams have insufficient ductility and are more expensive. Therefore, a hybrid beam reinforced with steel and FRP bars has been proposed recently. In this study, the flexural properties of steel bar RC beam, basalt FRP (BFRP) bar RC beam, and BFRP steel bars hybrid RC beams were studied based on numerical simulation. The effect of As/Af on the stress of longitudinal reinforcements, load–midspan curves, ductility, and overall performance of the hybrid RC beams is analyzed. Results indicated that the hybrid RC beams exhibited a second‐order stiffness after the steel bars yielded owing to the contribution of the BFRP bars. As As/Af increases, the ductility of the hybrid RC beam and the strength utilization of BFRP bars increase, and a preferable ductility and overall performance can be achieved when As/Af was close to 1.0. The theoretical calculation results of hybrid RC beams based on ACI, CSA, and GB codes are compared with the simulation results, and the accuracy of the ultimate flexural strength of the prediction results is verified. In addition, equations for predicting the deflection of hybrid RC beams are proposed, and they exhibit higher prediction accuracy compared to the prediction models based on the ACI code. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Materials Engineering / Cailiao Gongcheng is the property of Journal of Materials Engineering Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Bulletin of the Chinese Ceramic Society is the property of Bulletin of the Chinese Ceramic Society Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Mechanical properties of pure glass fiber wet-laid felts with no adhesives are relatively poor and limit the using. The aim of this study is to analyze the hybrid effects of glass/wood pulp wet-laid felt (GWFF) via papermaking technology. The influence of wood pulp fiber weight ratios on the physical properties of GWFFs is studied. The results show that GWFFs can obtain excellent uniformity when wood pulp fiber weight ratios are less than 50%. GWFFs with 20% wood pulp fiber weight ratios exhibit optimum break elongation, flexural property, and bursting strength. It also finds that tensile strength and Young’s modulus increase with wood pulp fiber weight ratios due to the effect of surface roughness of fibers and hydrogen bonds between fibers.

The impact property and residual flexural property of three-dimensional (3D) five-directional braided carbon/glass hybrid epoxy composites were studied. Four kinds of arrangement for carbon fiber and glass fiber in the axial yarn were designed. Taking pure carbon fiber composites (C/Ca) as the control, the rest of arrangements were that glass fiber and carbon fiber alternately arranged at the width direction (C/G1), glass fiber and carbon fiber alternately arranged at the thickness direction (C/G2), and only glass fiber appeared at the axial yarn (C/G3). Results showed that the C/G2 composite has higher impact energy absorption capacity, and the C/G1 composite has higher impact stress. The flexural properties of C/Ca composite are the best and that of C/G3 composite are the worst before impacting. This study is helpful for the structural design of composites in specific occasions. [ABSTRACT FROM AUTHOR]

The current study focuses on the investigation of the synergetic effect of graphene nanoplatelets (GNPs) and carbon nanotubes (CNTs) on the flexural properties, hardness and water absorption characteristics of glass fiber reinforced polymer (GFRP) laminated composite materials. The laminated composite materials were fabricated with various configuration of filler reinforcements using vacuum assisted hand lay-up technique. Further, micromechanical analysis was performed using Halpin-Tsai model to investigate the synergistic effect of CNT/GNP hybrid glass fiber reinforced epoxy nanocomposites. It was observed that the CNT and GNP reinforced hybrid composite exhibited highest value of flexural strength and hardness; the respective values being 38% and 29% higher in comparison to the neat epoxy composite. Furthermore, among GNP and CNT, the composite containing former reinforcement exhibited better mechanical properties. The composites containing nanoparticles also exhibited better water uptake characteristic, where the weight gain for hybrid composite was 1.004%, whereas, for neat epoxy composite, the weight gain was 1.210%. This was attributed to the ability of nanofillers to restrict the intermolecular movement of the surrounding GFRP composites, which delays the relaxation of polymer chains, thereby reducing the diffusion of tiny molecules through the composites. It was also observed that the addition of GNPs has a strong effect on the elastic properties of the hybrid glass fiber reinforced epoxy nanocomposite than the addition of CNTs. [ABSTRACT FROM AUTHOR]

Glass ionomer cement (GIC) releases fluorides and has good biocompatibility, carbonated drinks, sometimes known as fizzy drinks, are carbonated liquids that contain dissolved carbon dioxide, sweeteners, and natural or artificial flavoring. The aim of our study is to determine the flexural strength of GIC after immersing in carbonated beverages. Twelve samples of GIC filling material were used among which six samples prepared were from the Dtech brand and six were prepared from the Shofu brand for the in vitro study. Bar-shaped specimens were prepared from each group with the dimension of 2 mm × 2 mm × 25 mm. They were immersed in Sprite, fizz drinks, and in distilled water as a control group. The immersion period was 7 days. Then, the determination of maximum force and displacement was done using INSTRON E3000 (ElectroPuls) universal testing machine, then the collected data were used to determine flexural strength. The mean flexural strength of Dtech GIC was 24.84 ± 6.523 Mpa. The mean flexural strength of Dtech GIC was 18.57 ± 11.60 Mpa. The independent sample t-test showed that P = 0.247 (>0.05) which was statistically not significant. The flexural strength of GIC material decreased after being immersed in Sprite and fizz drinks.

Three-dimensional (3D) printed polymer-reinforced cementitious composites are expected to be used to improve the ductility of cement-based materials. However, research on the maximum flexural capacity and failure mode of lattice-reinforced cementitious composites remains insufficient. In this study, six types of cells with different volume fractions are designed, and mainly undergo bending and tensile deformation. According to the load characteristics during a three-point bending test, five kinds of graded lattice structures are designed. Moreover, a skin-lattice structure and uniform lattice structure are designed, and plain cement mortar is set to comprehensively evaluate the bending mechanical properties of graded lattice-reinforced cementitious composites. The crack evolution and failure mode of these composites under three-point bending load are studied using digital image correlation (DIC). The results show that compared with the uniform lattice, the graded lattice can improve the maximum bending capacity of cement-based materials, improve their cracking characteristics and failure modes during the bending process, and enhance their toughness while reducing the amount of required material. Compared with the plain cement mortar specimen, the graded lattice-reinforced specimen with the largest bending peak load is found to have a 175% increase in the bending peak load and a significant increase in the bending bearing capacity.

Unidirectional carbon fiber-reinforced polymer nanocomposites were developed by adding alumina (Al2O3) and silicon carbide (SiC) nanoparticles using ultrasonication and magnetic stirring. The uniform nanoparticle dispersions were examined with a field-emission scanning electron microscope. The nano-phase matrix was then utilized to fabricate the hybrid carbon fiber-reinforced polymer nanocomposites by hand lay-up and compression molding. The weight fractions selected for Al2O3 and SiC nanoparticles were determined based on improvements in mechanical properties. Accordingly, the hybrid nanocomposites were fabricated at weight fractions of 1, 1.5, 1.75, and 2 wt.% for Al2O3. Likewise, the weight fractions selected for SiC were 1, 1.25, 1.5, and 2 wt.%. At 1.75 wt.% Al2O3 nanoparticle loading, the flexural strength modulus improved by 31.76% and 37.08%, respectively. Additionally, the interlaminar shear and impact strength enhanced by 40.95% and 47.51%, respectively. For SiC nanocomposites, improvements in flexural strength (12.79%) and flexural modulus (9.59%) were accomplished at 1.25 wt.% nanoparticle loading. Interlaminar shear strength was enhanced by 34.27%, and maximum impact strength was improved by 30.45%. Effective particle interactions with polymeric chains of epoxy, crack deflection, and crack arresting were the micromechanics accountable for enhancing the mechanical properties of nanocomposites. [ABSTRACT FROM AUTHOR]

Glass ionomer cement (GIC) releases fluorides and has good biocompatibility, carbonated drinks, sometimes known as fizzy drinks, are carbonated liquids that contain dissolved carbon dioxide, sweeteners, and natural or artificial flavoring. The aim of our study is to determine the flexural strength of GIC after immersing in carbonated beverages. Twelve samples of GIC filling material were used among which six samples prepared were from the Dtech brand and six were prepared from the Shofu brand for the in vitro study. Bar-shaped specimens were prepared from each group with the dimension of 2 mm × 2 mm × 25 mm. They were immersed in Sprite, fizz drinks, and in distilled water as a control group. The immersion period was 7 days. Then, the determination of maximum force and displacement was done using INSTRON E3000 (ElectroPuls) universal testing machine, then the collected data were used to determine flexural strength. The mean flexural strength of Dtech GIC was 24.84 ± 6.523 Mpa. The mean flexural strength of Dtech GIC was 18.57 ± 11.60 Mpa. The independent sample t-test showed that P = 0.247 (>0.05) which was statistically not significant. The flexural strength of GIC material decreased after being immersed in Sprite and fizz drinks. [ABSTRACT FROM AUTHOR]

Wood–plastic composite (WPC) is a kind of composite material that is made of plastic and wood fiber or wood powder. Because it is mothproof, is resistant to corrosion, and has plasticity, among other advantages, it has been researched and used increasingly in building materials. The flexural property of WPC is an important subject in evaluating its mechanical properties. In this paper, wood–plastic raw materials and processing technology are introduced; the internal and external factors of WPC which affect the flexural properties are analyzed; the different ways of enhancing the bending capacity, including the surface pretreatment, addition of different modifiers (compatibility agent and coupling agent) etc. are summarized; and the methods of operation and strengthening effect are analyzed. This work provides a reference for further research in related fields. [ABSTRACT FROM AUTHOR]

The long cycle of manufacturing continuous carbon fiber-reinforced composite has significantly limited its application in mass vehicle production. High-pressure resin transfer molding (HP-RTM) is the process with the ability to manufacture composites in a relatively short forming cycle (<5 min) using fast reactive resin. The present study aims to investigate the influence of HP-RTM process variables including fiber volume fraction and resin injection flow rate on void characteristics, and flexural properties of manufactured CFRP components based on experiments and numerical simulations. An ultrasonic scanning system and optical microscope were selected to analyze defects, especially void characteristics. Quasi-static bending experiments were implemented for the CFRP specimens with different void contents to find their correlation with material's flexural properties. The results showed that there was also a close correlation between void content and the flexural strength of manufactured laminates, as the flexural strength decreased by around 8% when the void content increased by ~0.5%. In most cases, the void size was smaller than 50 μm. The number of voids substantially increased with the increase in resin injection flow rate, while the potential effect of resin injection flow rate was far greater than the effect of fiber volume fraction on void contents. To form complicated CFRP components with better mechanical performance, resin injection flow rate should be carefully decided through simulations or preliminary experiments. [ABSTRACT FROM AUTHOR]

In this study, the flexural behavior of high performance concrete (HPC) beams under the combined effect of repeated loading and chloride dry-wet exposure is investigated. From the material perspective, a series of cubic specimens were subjected to axial cyclic loading with a stress level of 0.4 and subsequently exposed to chloride dry-wet cycles. The results revealed that the repeated loading would cause significant internal damage, as indicated by the measured relative dynamic modulus. Additionally, the compressive strength of cubic specimens showed a first rising and then falling process during the chloride dry-wet cycles. By comparison, a relation model between compressive strength and relative dynamic modulus is proposed for damaged HPC. Furthermore, ten HPC beam specimens were fabricated and subjected to a similar combined exposure to repeated-loading and chloride dry-wet cycles. These beams were then loaded to failure using a four-point loading mode and the findings indicate that the repeated loading history led to initial cracking damage and reduced the flexural performance of tested HPC beams. Meanwhile, the chloride dry-wet cycles could improve the concrete strength and consequently enhance the specimen's capacity. Their combined effect on the beam's ultimate loads was established considering the strength damage of HPC. Finally, an analytical derivation was proposed to capture the deflection of tested beams under the combined effect, which took the damage in the section's short-term stiffness into account, resulting in a more accurate prediction of deflection. • A long-term aggressive test was performed on ten HPC beams under the combined effect of repeated load and chloride exposure. • A relation model between compressive strength and relative dynamic modulus was proposed for damaged HPC. • The ultimate loads for HPC beams without significant corrosion could be assessed directly with the damage in compressive strength. • A damage-based stiffness model for predicting flexural deflection was proposed for HPC beams. [ABSTRACT FROM AUTHOR]

A new‐type flame retardant DEZ of bi‐DOPO compound containing bi‐hydroxy and two amino groups, was synthesized from terephthalonitrile, hydroxylamine hydrochloride, and 9,10‐dihydro‐9‐oxa‐10‐phosphaphenanthrene‐10‐oxide, and used with curing agent 4,4′‐diamino‐diphenylmethane to prepare flame retard epoxy resin (EP) composites. 1H and 31P nuclear magnetic resonance spectra and Fourier transform infrared spectra have determined the chemical structure of DEZ. The properties of cured EP composites were explicitly evaluated by differential scanning calorimeter, thermogravimetric analysis, the limiting oxygen index (LOI), vertical burning (UL‐94) test, cone calorimetry test, and flexural test. The 1 wt% addition of DEZ could improve the EP composites by almost 14.4% of flexural strength and 29.6% of flexural modulus, respectively. The LOI of EP composites with 5 wt% of DEZ was 29.7% and EP composites reached a V‐0 rating in the UL‐94 test, as well as total heat release was decreased by 11.2%. All EP modified by DEZ exhibited a blow‐out effect in the combustion process, which was due to the release of pyrolysis gases and incombustible gases containing phosphorus radicals and nitrogen compounds. [ABSTRACT FROM AUTHOR]

Copyright of Bulletin of the Chinese Ceramic Society is the property of Bulletin of the Chinese Ceramic Society Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Southeast University / Dongnan Daxue Xuebao is the property of Journal of Southeast University Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Four kinds of sandwich-structured C/C-SiC and C/C-SiC-ZrC composites with or without a SiC interphase deposited by isothermal chemical vapor infiltration (ICVI), were designed and fabricated by a joint process of electromagnetic coupling chemical vapor infiltration (ECVI) and precursor infiltration and pyrolysis (PIP). The fabricated composites are macroscopically nonhomogeneous materials with low density, high strength and low ablation rate. The interphase and matrix constituents had remarkable effects on the mechanical and ablation properties of these composites. The C/C-SiC composites with an ICVI-SiC interphase exhibited the highest flexural strength of 306.5 MPa. While the C/C-SiC-ZrC composites with the interphase showed the best anti-ablation performance with low linear and mass ablation rates of 0.37 μm/s and 0.04 mg/cm2·s, respectively, after the ablation for 500 s under an oxyacetylene flame test at around 2000 °C. [ABSTRACT FROM AUTHOR]

Brittle materials generally exhibit size effects, and the mechanical properties of these materials degrade significantly with an increase in size. However, the mathematical law governing the attenuation degree of mechanical properties with the increase in size is still unknown. In this study, maximum loads of differently sized ceramic test strips were subjected to three point bending tests under two working conditions of equal spans and span amplifications, respectively. Subsequently, the theoretical maximum loads of materials were calculated using the finite element method (FEM). By calculating the difference between the calculated values and the actual maximum loads, the attenuation of mechanical properties of ceramic samples were observed. The results show that the theoretical mechanical properties and the performance attenuation caused by the size effect tend to increase according to the following equation: y=ax3+bx2+cx+d. Therefore, mechanical properties and performance attenuation of any sample exhibiting a size within the experimental range can be predicted by a mathematical law, which was obtained through mechanical tests results of four samples with different sizes. The obtained mathematical law holds great significance for predicting the mechanical properties of materials under size effects. [ABSTRACT FROM AUTHOR]

The research work aims to utilize one of the cheapest and most abundantly available natural fibre, sisal fibre, to fabricate a hybrid nanocomposite possessing high performance efficiency. Glass fibre (GFC), sisal fibre (SFC) and hybrid glass/sisal fibre reinforced epoxy laminate composites (HFC) were prepared and subsequently, three of the most promising nano-fillers, MXene (HFC _MXN ), Graphene nanoplatelet (HFC _GNP ) and Multi-walled carbon nanotube (HFC _CNT ), were added into the hybrid composite. The fabricated composites were comprehensively assessed and analysed for their mechanical properties, swelling and flammability behaviour. It was observed that the glass fibre reinforced composite had lowest void content (6.3%) and glass/sisal fibre reinforced laminate had the highest void content (17.2%). The addition of nano-fillers did not further enhance the void content owing to the relatively uniform dispersion of the nanoparticle, which was particularly ensured during the whole fabrication process. The incorporation of nano-fillers led to a significant enhancement in the mechanical properties; tensile and flexural strength being highest for composites containing two dimensional nano-fillers. The GFC exhibited minimum weight gain (2.25%) and least swelling thickness (1.66%) upon soaking. Among hybrid composites, nano-filler reinforced composites had relatively less weight gain post in comparison to the hybrid composite without any nano-filler. HFC _GNP had a weight gain of 6.69%, as opposed to 8.51% observed in case of HFC. The nano-fillers acted as an effective water barrier that reduced the tendency of water absorption. Furthermore, upon flammability test it was found that the burning rate decreased in order of GFC, HFC, HFC _CNT , HFC _MXN , HFC _GNP and SFC. The addition of nano-fillers led to a decrease in the burning rate owing to the promising flame retardant properties of graphene which suppressed flame propagation and helped in extinguishing the flame.

Due to its excellent mechanical properties such as ultra-high strength and ultra-high ductility, high-strength and high-ductility cementitious composites (HSHDCC) have been widely used in recent years. It has received extensive attention in the field of seismic reinforcement and repair of building structures. However, the high cost of HSHDCC is one of the bottlenecks for its large-scale engineering application. one. A new type of HSHDCC material was prepared by introducing calcium carbonate whiskers with high strength, high elastic modulus and low cost. must have an effect on the flexural properties of HSHDCC. The study found that the flexural strength of HSHDCC decreased with the increase of the water-binder ratio, but its ductility increased with the water-binder ratio. The flexural cracks of HSHDCC gradually saturate with the increase of water-binder ratio. The introduction of calcium carbonate whiskers improves the bending resistance of HSHDCC Calcium carbonate whiskers generate more microcrack sources through microscopic action mechanisms such as whisker pullout, crack deflection and crack bridging, and improve the stable propagation energy of cracks. The ductility of HSHDCC has been significantly improved by improving the multi-slit cracking ability and bending deflection hardening behavior of HSHDCC. [ABSTRACT FROM AUTHOR]

Alkali-treated discontinuous cellulosic fibers (jute and sisal)-based heat-treated silanized fly ash-dispersed hybrid polyester composites were fabricated using a compression molding technique. The morphological features were observed using a scanning electron microscope and a high-resolution transmission electron microscope. The bulk mechanical testing namely, microhardness, tensile, flexural as well as Izod impact was successfully executed. The significant effect of the filler (cellulosic fibers as well as modified fly ash) dispersion within the polymeric matrix with respect to mechanical properties was thoroughly examined in this present investigation. [ABSTRACT FROM AUTHOR]

Carbon fiber paper reinforced thermoplastics (CPT) have broad application prospects because of its simple production process and good mechanical properties. Currently, polyamide 6 (PA6) is a promising matrix for CPT and is widely used for mass-production. However, the performance of CPT materials in marine and harsh environments must be evaluated because of its environmental sensitivity. In this study, the seawater absorption of CPT was analyzed using Fick's diffusion law. The flexural properties of CPT in harsh and marine environments were studied by three-point bending. Based on the results, it was concluded that seawater and high temperatures have negative effects on the flexural properties of CPT. Microscopy results showed the mechanisms of failure under the action of seawater and high temperatures. Droplet test was employed to analyze the interfacial shear properties between the fiber and resin. The results showed that after seawater immersion, the interfacial shear strength had a discernable decrease. [ABSTRACT FROM AUTHOR]

The standardized acrylonitrile-butadiene-styrene (ABS) or polycarbonate (PC) resin disk with added flame retardants (FRs) has a potential to be a suitable tool for predictions of both aging of the plastic materials and release rate of a flame retardants exposed under different outdoor and indoor conditions. The experiments examined the dynamics and kinetics of the release of dechlorane plus, tetrabromobisphenol A, triphenyl phosphate and antimony trioxide as FRs from a standardized plastic disk before and after exposure to artificial sunlight. Assessments were carried out independently to measure changes in the content of flame retardants and monitor the flame retardancy and flexural properties after exposure (60 W/m2) over a period of 200 h and 500 h, which are reasonable to predict a short-time tendency and to receive any advice for a safe re-use. The releases of three organic flame retardants and four elements (Cl, Br, P and Sb) from weathered ABS and PC disks were very limited, except for surface delamination and resin microparticles. Triphenyl phosphate was stable without hydrolysis, while the degradation of tetrabromobisphenol A was observed (approximately 20% decrease for ABS disk and approximately 50% decrease for PC disk). During the study, no significant differences in the flame retardancy and flexural properties of the disks could be detected. In practice, the results obtained from disks of acrylonitrile-butadiene-styrene or polycarbonate resin with selected flame retardants used in specific conditions may provide technical expertise regarding weathering processes. [ABSTRACT FROM AUTHOR]

The application of C/C-SiC composites remains a challenge because of the poor mechanical properties induced by the liquid silicon infiltration method. In this study, a thick high textured pyrolytic carbon (HT PyC) interface manufactured by chemical vapor infiltration (CVI) was used to protect the carbon fibers and improve the flexural properties. The microstructure of HT PyC, its flexural properties, and its associated strengthening and toughening mechanisms were analyzed on the C/C-SiC composites. The results showed that the bending strength of the C/C-SiC composites was 344.74 MPa, which is nearly 31.82% higher than that of C/C composites. The fracture mode transformed from brittle fracture to pseudoplastic fracture owing to the addition of SiC, and the C/C-SiC composites maintained a better toughness compared to C/C composites. Multiple mechanisms of strength and toughness improvement were found to be responsible for the excellent performance of the C/C-SiC composites. The HT PyC interface played a critical role in the excellent flexural properties. The strong bonding among the carbon layers and high interfacial strength between the fiber and HT PyC led to the increase of strength. Besides, the improvement in toughness was attributed to the multiple effects of the carbon-layers deformation, cracks deflection and propagation caused by the bridging areas, sublayers, nano- and micro-scale cracks. [ABSTRACT FROM AUTHOR]

Ta 0.78 Hf 0.22 C solid solution ceramic was synthesized and introduced into carbon/carbon (C/C) composites by polymer infiltration and pyrolysis (PIP). Effect of the introduction of Ta 0.78 Hf 0.22 C on the microstructure, ablation resistance, and flexural performance of C/C composites were investigated. Results showed that the flexural strength and modulus of the composites were increased by 108 % and 117 %, respectively, after adding Ta 0.78 Hf 0.22 C solid solution into C/C composites. In addition, the introduction of Ta 0.78 Hf 0.22 C improved the ablation resistance of C/C composites under oxyacetylene ablation environment, over 2200 °C. The linear and mass ablation rates were decreased 73 % and 70 %, respectively. The oxide with low melting point, Ta 2 O 5 , exhibited good sealing and oxygen-barrier capacity, and the formation of new solid solution oxide particles, Hf 6 Ta 2 O 17 , could pin cracks during ablation, both of them were contributed to better ablation resistance of modified C/C composites. [ABSTRACT FROM AUTHOR]

Carbon fiber paper–reinforced thermoplastics (CPTs) are widely used because of their formability and superior mechanical properties. Polyamide 6 (PA6) is used as a resin matrix in carbon fiber-reinforced composites owing to its good mechanical properties and adhesion with the carbon fibers. However, PA6 tends to absorb moisture because of the presence of hydrophilic groups in the polymer backbone. This may negatively affect the mechanical and interfacial properties and reduce the service life of CPTs products. Therefore, this research focuses on the long-term applicability of CPTs in aqueous environments. In this study, CPT plates were fabricated by compression molding and subjected to long-term aging in a hydrothermal environment, and the effects of long-term aging on the properties of the composite were investigated. The water absorption behavior was found to follow Fick's diffusion law, the interfacial property was determined by the microdroplet test, the surface morphology was analyzed by 3D laser scanning microscopy, the physicochemical properties were determined by differential scanning calorimetry and Fourier transform infrared spectroscopy, and the flexural properties were determined by the three-point bending test. A modified rule of mixture and the Kelly–Tyson model were applied to describe the changes in the flexural properties. The findings of this study provide guidance for the further application of CPTs products. [ABSTRACT FROM AUTHOR]

In this study, the gradually anchored technique is combined with the prestressed near-surface-mounted (NSM) carbon fiber-reinforced polymer (CFRP) strengthening technique to reduce the stress concentration caused by prestress transfer at the CFRP end section and improve the failure mode and bearing capacity of strengthened beams. Flexural performance tests are conducted on one fully prestressed and six gradually prestressed NSM CFRP-strengthened reinforced concrete beams under static loads. The influencing factors include the gradient prestress, CFRP bond length, concrete cover thickness, and steel reinforcement type. The failure mode, characteristic load, shear stress distribution at the CFRP end section, as well as the crack development under prestress and load are analyzed. The test results indicate that the gradually prestressed beam is superior to the fully prestressed beam in reducing the stress concentration at the CFRP end, thereby inhibiting the development of cracks at the CFRP end, improving the bearing capacity, and delaying the separation of concrete cover. The bearing capacity and ductility of the strengthened beams are significantly improved, with a maximum increase of 35% and 100.33% for them respectively, confirming the effectiveness of the gradually prestressed NSM CFRP strengthening technique. Finite element analysis is conducted to further investigate the effect of gradient prestress on flexural performance of strengthened beams and propose design suggestions. • Static load tests were performed on RC beams strengthened with gradually anchored prestresses NSM CFRP. • Prestress setting parameters and reinforcement layout of RC beams were studied. • Finite element model was established, and the recommended parameters of gradient prestress were given. [ABSTRACT FROM AUTHOR]

Iron-based shape memory alloys (Fe-SMAs), which are emerging as a novel class of self-prestressing materials dispensed with in situ tensioning, have been studied primarily in the field of structural strengthening. In addition, the self-prestressing characteristics of the Fe-SMA rebars are extremely promising for new concrete bridges that are seriously affected by prestress loss during their service life. Therefore, the effect of self-prestress generated by embedded Fe-SMA rebar was experimentally investigated by six concrete T-beam. The influence of factors such as the activation status, prestress value, and diameter of the Fe-SMA rebar on the flexural performance was investigated. The variation laws of the cracking load, yield load, ultimate load, and stiffness were analyzed. The results illustrated that the activation of the Fe-SMA rebar had a remarkable influence on delaying beam cracking. Under the same load (130 kN), the specimens with an activated Fe-SMA rebar exhibited a remarkable reduction exceed 30% in crack width compared to those with an unactivated Fe-SMA rebar. Following the activation, the cracking load, yield load, ultimate load, and stiffness increased to varying extents,. The Fe-SMA, characterized by its remarkable ductility, exerted a beneficial influence on the deformation capability of the beams. This enhancement became notably conspicuous following Fe-SMA activation. Analysis of the cracking load and concrete strain during the activation process indicated that the prestress of the embedded Fe-SMA rebar closely approximated the values observed in the rigid confinement. The calculated flexural capacity agreed with the experimental data, and the proposed calculation method can provide a reference for subsequent research. • The flexural properties of T-shaped concrete beams reinforced with Fe-SMA rebar were investigated. • The activation of the Fe-SMA rebar had a remarkable influence on delaying beam cracking • The Fe-SMA exerted a beneficial influence on the deformation capability of the beams. • The method for calculating the flexural capacity of a T-beam with a Fe-SMA rebar is proposed. [ABSTRACT FROM AUTHOR]

A new type of stay-in-place formwork (SIPF) concrete beam was proposed; this beam consists of a U-shaped shell made of basic magnesium sulfate cement-based composite (BMSCC), a perforated square steel pipe and core concrete. The prefabricated shell and square steel pipe form a composite SIPF, the steel pipe replaces the longitudinal reinforcement and hoop reinforcement, and the combination beam can be formed after pouring the core concrete inside. Four-point bending tests of two SIPF beams and one reinforced concrete (RC) comparison beam were conducted using longitudinal steel consumption as a parameter. The results showed that the SIPF beams exhibited a typical ductile damage pattern and that the precast shell was reliably bonded to the core concrete without spalling. The cracking load was increased by 198.25 %, the yield load by 66.3 %, and the ultimate load by 64.7 % for the same amount of steel used in the steel pipe instead of the reinforcing cage. After the equivalent longitudinal reinforcement rate of 1 % at the bottom of the SIPF beam was increased to 1.25 %, the flexural capacity increased by 9.65 %. By introducing the restraining stress coefficient and stiffness contribution coefficient, a formula for calculating the flexural capacity of the positive section of the SIPF beam was established. • A new type of SIPF concrete beam was proposed. • BMSCC is environmentally friendly, high strength and durable. • The precast shell was reliably bonded to the core concrete without spalling • The SIP beam can significantly increase the cracking load and ultimate load. [ABSTRACT FROM AUTHOR]

Cellulose nanofibers (CNF) have recently attracted attention as one of the reinforcements for composite materials. However, the same as other nanofibers, CNFs can be easily agglomerated and the nano-level defibration is necessary to obtain their outstanding properties in polymer matrices. To overcome this issue, two major defibration methods, chemical and mechanical defibration have been considered. The chemically-defibrated CNF is expensive and so prevents the practical realization of CNF as general-purpose products. Therefore, the mechanical defibration method by a clean low-cost water jet was focused on. Mechanically-defibrated CNF reinforced epoxy resin matrix (Epoxy-CNF) composite was fabricated via mechanical mixing and the variation of their tensile and flexural properties with different CNF volume fractions was evaluated. The tensile and flexural moduli of the epoxy resin were increased by CNF addition, while the fracture elongation was decreased. The calculated ultimate tensile strength (UTS) and ultimate flexural strength (UFS) of the Epoxy-CNF composites, using the aspect ratio of the agglomerated CNF clusters, indicated the validity of the random dispersion model considering the agglomerated CNF as one whole fiber. It seems that epoxy resin is enhanced by the mechanical interaction when the CNF volume fraction is higher than 0.37 vol.%. [ABSTRACT FROM AUTHOR]

Carbon fiber reinforced thermoplastic (CFRTP) has a good electromagnetic shielding property due to its higher conductivity and broad absorption frequency bandwidth while presenting high specific strength and stiffness, their easy process-ability, cost-effectiveness, and recyclability. In the present study, laminated CFRTP made of carbon fiber-polyamide 6 unidirectional tape (UD tape) were fabricated with different laminate configurations and arrangements (unidirectional, bidirectional, and quasi–isotropic) and then were compared with randomly chopped-tape CFRTP. Thereafter, estimated electromagnetic interference shielding effectiveness (EMI-SE) using Simon formalism and flexural properties of CFRTP were evaluated. The result showed a remarkable total EMI-SE of 31–44 dB in the Ultra High Frequency (UHF) range and strongly correlated with the laminate configuration of CFRTP. Whereas, randomly chopped-tape CFRTP has a lower total EMI-SE of 23–27 dB in the same frequency range. In addition, the flexural test result showed the flexural strength and modulus are strongly influenced by the tape layer configuration in the laminated CFRTP. Moreover, microscopy analysis was also conducted to verify the interlaminar structure and fiber-to-fiber contact in the composite. In conclusion, laminated CFRTP made of UD tape can be considered as electromagnetic interference shielding material for both functional and structural applications. [ABSTRACT FROM AUTHOR]

Flaxseed plants are widely grown globally due to the beneficial seed oil derivatives for human and animal consumption and other industrial uses. However, plentiful flaxseed straws are annually burnt after the harvesting of seeds, lacking utilization of the abundant flaxseed fibers, resulting in wastage of a valuable fiber resource and drastic increase in environmental pollution. In this study, initially the chemical composition and mechanical property of flaxseed fiber bundle were investigated, which resulted as 40.11% cellulose, 28.27% hemi-cellulose, 15.08% lignin, 6.3% pectin, 3.1% wax, and the tensile strength of 1.14 cN/dTex. The surface modification treatment was carried out with concentrations of 10 g/L and 20 g/L sodium hydroxide (NaOH). Later, flaxseed fiber bundles reinforced Polybutylene Succinate (PBS) resin composites were fabricated by thermal compression method. The tensile strength of untreated flaxseed fiber bundle/PBS composites was 78.2 MPa, while the flexural strength of 20 g/L NaOH treated flaxseed fiber bundle/PBS composites showed 84% increment from 26.70 MPa to 49.16 MPa. The scanning electron microscopy (SEM) images revealed significantly rougher surface morphology and stronger interfacial bonding of the alkali treated fiber bundles with matrix. The good mechanical properties observed demonstrated the absolute potential of resultant composites reinforced by flaxseed fiber bundles for utilization in the civil and industrial applications. [ABSTRACT FROM AUTHOR]

To improve the applications of beetle elytron plates (BEPs, which are biomimetic sandwich plates inspired by beetle elytra), the flexural performance and its synergistic mechanism of multibody molded BEPs were investigated via cantilever testing and finite element method (FEM). The results are summarized as follows. (1) Although debonding damage causes failure of the multibody molded BEPs and honeycomb plate and the reasonable range of trabecular size for BEPs is narrow, both the optimal loading capacity per mass and failure deformation of the BEPs are over two times those of the honeycomb plate. (2) A flexural synergistic mechanism is revealed in the trabecular-honeycomb core structure of BEPs; this mechanism causes the maximum deformation of core structure to gradually transfer from the honeycomb wall to the trabeculae with the increase in η (the ratio of the trabecular radius to the distance between the center points of two trabeculae), which means the different stretching behaviors in these core structures. (3) Unlike the compressive mechanism of BEPs, by controlling and balancing the deformation degrees of the trabeculae and honeycomb walls, the flexural mechanism achieves a minimum core deformation and an optimal flexural performance. These results suggest a qualitative relationship between the deformation behavior of trabecular-honeycomb core structure and bending performance of the whole BEP, and provide a solid foundation for subsequent research and the considerable application potential of this biomimetic sandwich structure in many fields. [ABSTRACT FROM AUTHOR]