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Green composites based on ramie fiber yarn and cellulose acetate resin were prepared via hot pressing. The ramie fiber yarns were treated with NaOH and 3-glycidoxypropyltriethoxysilane. The effect of surface treatment on the fiber adhesion to the resin surface and the mechanical properties of the green composites were studied. The chemical properties of the modified ramie fiber yarn were studied via Fourier-transform infrared (FTIR) spectroscopy. The adhesion performance between the fiber and resin was evaluated. The tensile strength of the composites was measured through tensile testing. A single-fiber tensile experiment was used to determine the influence of the tensile strength of the single fibers after surface-treatment. The surface morphology changes were observed via scanning electron microscopy. The results showed fiber–resin adhesion was improved by the surface treatments. However, the surface treatments negatively affected the single-fiber mechanical properties, with the alkali treatment causing greater damage than the silane treatment.

Co-extrusion technique is used to combine carbon fiber tows and thermoplastic polyurethane (TPU) blends into composite carbon fibers (CCFs). The TPU blends serve as the shell and the carbon fiber tows serve as the core. CCFs are fabricated into woven composites and knitted composites with electromagnetic interference shielding effectiveness (EMI SE). The effects of the content of carbon fiber tows on different fabrics are examined. The failure mechanism of CCFs is improved as the fiber slippage along the axial direction replaces the fiber fracture. Fabrics made of CCFs are soft. The laminated woven composites have an average EMI SE of -27.20 dB at 0–3000 MHz and -44.99 dB at 2450 MHz, suggesting a good EMI attenuation capability. This study proposes the use of co-extrusion technique followed coating and fabrication of carbon fibers. This brand-new concept would be vital in the development of carbon fiber composites.

Windmill palm fiber is a kind of multicellular lignocellulose fiber material. Multiscale structure is an essential factor in mechanical properties and applications. The multiscale fibrils under sulfuric acid treatment had been prepared to improve the understanding of the macro-, micro-, and nanoscale structure of the windmill palm fiber. Scanning electron microscopy, atomic force microscopy, wide-angle X-ray scattering, and X-ray diffraction were used to analyze these samples’ structure. Furthermore, the result showed that the elementary fibril diameter was 4–10 nm, whereas that of the microfibrils was 20–70 nm. The diameters of macrofibril and macrofibril bundles were 0.4–1.0 µm and 1.2–5.5 µm, respectively. The elementary fibril assembled into spiral microfibril with an angle of 46°. The crystallinity of nanofibril extracted from windmill palm fiber was about 62%.

This study focused on the m-Aramid/p-Aramid blend ratio of the fabrics, clarified the quantitative relationship between UV exposure and strength retention, and developed a mathematical model to calculate tensile strength from an arbitrary amount of UV exposure energy. The results of tensile strength tests before and after UV exposure showed that the decrease in tensile strength due to UV degradation depended on the combination of p-Aramid and m-Aramid blend percentages. Tensile strength for all blend ratios decreased exponentially with UV exposure energy and was within the range of results for fabrics with p-Aramid 100% and m-Aramid 100%. The retention fraction of tensile strength, which represents the tensile strength after UV exposure relative to the initial tensile strength, decreased exponentially with increasing the fraction of UV exposure energy for all fabrics used in this study. Fitting the retention fraction of tensile strength to the fraction of UV exposure energy, two groups of fabrics were classified based on m-Aramid blends of 40% or more and 60% or less. This model can predict the tensile strength of firefighter clothing fabrics that retain high mechanical strength when exposed to UV light and design the strength of firefighter clothing with consideration of degradation over time.

The mechanical properties of continuous fiber-reinforced thermoplastic (C-FRTP) composites are commonly lower than those of continuous fiber-reinforced thermosetting plastic (C-FRP) composites. We have developed a new molding method for C-FRTP. In this study, pre-impregnated materials were successfully prepared by polymer solution impregnation method and, finally, C-FRTP was fabricated. The viscosity of the thermoplastic matrix was decreased to approximately 3dPa×s, the same level of epoxy, and the fiber volume fraction was increased from approximately 45 to 60%. The cross-section of specimens were polished by an ion milling system and impregnation condition was investigated by scanning electron microscopy (SEM). The micrographs suggested that thermoplastic polymer was impregnated to every corner of the fiber, and no void was found on the cross-section. It revealed that void-free composites with perfect mechanical properties can be manufactured with this new molding method. All specimens were submitted to a mechanical measuring equipment, and the mechanical properties of the composite specimens were investigated. Mechanical analysis revealed that tensile property and flexural property of C-FRTP were enhanced up to the same level with C-FRP.

The compressive strength of unidirectionally FRP is lower than the material’s tensile strength. Application of a bending load to a mechanical structure’s FRP shell results in a tension side and a c...

In modern age, prosperous business, industrial, social, and leisure activities improve and ensure the quality of lives considerably, but are inevitably accompanied with insecurity and dange...

Protective textiles require massive consumption of fibers and fabrics, which is responsible for diverse highstrength fabric waste. Wrongly arranged disposal of textile waste is equivalent to the waste valuable resource while causing environmental pollutions. Aramid selvages are worthwhile recycling and used in this study. They are scattered into Aramid staple fibers and mixed with low melting point polyester (LMPET) fibers to form the Aramid matrices employing the nonwoven process. The matrices are added to different combinations to form Aramid composite matrices and hybrid-fiberreinforced composite boards. The process of shearing, crowding, and friction helps improve the mechanical properties of the composite boards according to the evaluations of conducted tests. With the premise of minimum damage to the fibers, this study uses recycled Aramid waste to produce composite boards that have features of high performance and low production cost. As a test result, the hybrid-fiber-reinforced composite boards with 90 wt% of recycled Aramid fibers have the optimal mechanical property and static puncture resistance.

The quantitative relationship between the fraction of UV exposure energy and the retention fraction of tensile strength was investigated on the m-Aramid/p-Aramid blend ratio of spun yarn. An exponential equation to calculate tensile strength from an arbitrary UV exposure energy is evaluated for yarns and fabrics. The spun yarns were exposed to UV light using a xenon-arc weathering meter. The retention fraction of tensile strength decreased exponentially with increasing the fraction of UV exposure energy. Curve fitting of the retention fraction of tensile strength to the fraction of UV exposure energy revealed two groups of degradation coefficients based on the blending ratio of m-Aramid/p-Aramid. The correlation between the degradation coefficients (αy and αf) of spun yarn and fabrics can be linearly regressed. The constant of proportionality in linear regression is considered to be the gap between the structure and the breaking mechanism of the fabric relative to yarn breakage. Based on the correlation between the degradation coefficients of spun yarn and fabrics and a mathematical model of the tensile strength of the spun yarn, the tensile strength of fabrics at a given UV exposure energy can be estimated from the tensile strength of the yarn.

High-performance yarns are widely used to produce protective fabrics, including stab-resistant materials. The most common approach to studying the mechanism of puncture prevention is to use simulation to assist analysis. However, the anisotropy of the yarn is often overlooked during simulation owing to various factors. In fact, there is a marked difference between the axial and radial properties of a yarn. This may lead to large errors in research. In the present study, a composite material with a grid structure for puncture analysis was designed to investigate the influence of yarn anisotropy on the accuracy of simulation results. The present study combined an actual experiment with a simulation. In the actual experiment, Kevlar yarn/epoxy resin was used to prepare a mesh composite with a spacing of 1 mm. In the simulation, a 1:1 simulation model of composite material was established using finite element software. A simulated puncture experiment was conducted based on the actual experimental conditions and material parameters. After considering yarn anisotropy, the simulation results were closer to the actual experimental results. The simulation revealed that the main failure modes of the mesh material were the fracture of the resin and the bending deformation of the yarns at the junctions, while the surrounding areas were almost unaffected.

In this work, polyetherimide (PEI) nanoparticles were prepared on carbon fiber (CF) surfaces via an evaporation-induced surface modification method. Scanning electron microscopy analysis revealed that the average diameter of the PEI nanoparticles linearly increased with increasing PEI concentration. This finding indicated that the nanoparticle size on the CF surface could be controlled by changing the PEI concentration used in the surface modification process. The possible formation mechanism of the PEI nanoparticles on the CF surfaces was also investigated by cross-section observation of CF using field-emission scanning electron microscopy (FE-SEM). In addition, the single fiber strength and interfacial shear strength between the CFs and epoxy resin were observed to increase after the surface modification. The interfacial shear strength (IFSS) results between treated CF before and after heating show that the presence of PEI nanoparticles had a great influence on IFSS. At a PEI concentration of 0.2%, the IFSS value reached its maximum value, 44.02% more than that of desized CF.

In this study, three differently composed polyurethane (PU) composites are developed and then compared with the pure PU foam in terms of combustion resistance and mechanical properties using the compression test, the drop-weight impact test, the horizontal burning test, and the sound absorption test. Flame-retardant fabric (FRF)-PU is composed of PU foam that is enclosed with two cover sheets of FRFs. FR-PU10 is composed of PU foam that contains 10 wt% of flame-retardant agents. FRF-PU10 is composed of PU foam containing 10 wt% of flame-retardant agents and enclosed by two covers sheets of FRFs. Based on the test results, both FR-PU10 and FRF-PU10 are structurally stabilized and have good combustion resistance. The sample using FRFs as cover sheet had the same combustion resistance property and better compression resistance as the sample using flame-retardant agent. The carbonized layer extinguishes the alighted samples and stops the fire spread right after they are out of the source of fire, suggesting the FRF-PU10 is flame retardant. In addition, FRF-PU10 is easier to process and healthier because of the low use of flame retardants. Therefore, in this study, we proposed PU foam composites have good mechanical and flame-retardant properties and are a suitable candidate for productions of vehicles, plants, construction, and staple merchandises.

Poly( p -phenylene benzobisoxazole) (PBO) fibers were modified using the evaporation-induced surface coating method. Through this new method, nano-TiO 2 particles encapsulated with polyetherimide (PEI) chains were firmly adsorbed on the fiber surface. The coating thickness was calculated through the observation of the fiber cross-section by transmission electron microscope. The surface morphologies of the fibers were examined using scanning electron microscopy and field-emission scanning electron microscopy, the surface chemical composition was analyzed with energy dispersive X-ray spectroscopy. The surface roughness was analyzed with atomic force microscopy, and thermogravimetry and single fiber tensile strength were also measured. The results indicate that besides some nanospheres resulted from the initial agglomeration of PEI-encapsulated nano-TiO 2 , a uniform coating layer with thickness of 84 nm was formed by absorption of polyetherimide (PEI)-encapsulated nano-TiO 2 . This coating method changed the surface morphology of the PBO fibers, enhanced the surface roughness, and increased the poor UV resistance of untreated PBO fibers.

There is limited information on the recycling of continuous fiber-reinforced thermoplastics (FRTPs). Furthermore, existing research has been conducted in laboratories on a very small scale. In this article, we propose an effective and simple technology for recycling of FRTPs, which can be conducted on a large scale. To accelerate the rate of resin dissolution, prepared FRTPs were cut into small pieces. The obtained pieces were used to manufacture recycled chopped fabric tape-reinforced thermoplastics (R-CTTs). The feasibility of the recycling technology was confirmed by comparing the mechanical properties of the composites made from virgin materials (virgin chopped fabric tape-reinforced thermoplastics (V-CTTs)) and recycled materials. There was a significant improvement of the tensile properties with the increase of the specimen thickness. The strength of the materials was more sensitive to the length of the chopped tape than the modulus. Fibers in both V-CTT and R-CTT were well connected with the resins, as confirmed by scanning electron microscopy.

Diverse products are delivered from the production place to different destinations, during which any impacts or shakes easily lead to the damage of products. Buffering packaging materials are thus used to absorb the energy caused by damage, thereby preserving the goods. Buffering packaging materials are commonly made of plastics and foams, which are the materials that have limited buffering effect and cannot be repetitively used. Therefore, this study proposes eco-friendly buffering sandwich-structured composites using thermoplastic polyurethane honeycomb grids and three-dimensional crimped, flame-resistant polyester nonwoven fabrics. Thermoplastic polyurethane honeycomb grids have advantages of a lightweight, a high strength, and high impact resistance. Thus, thermoplastic polyurethane honeycomb grids can be combined with flexible nonwoven fabrics that features ease of process to form environmentally friendly buffering packaging materials. Polyester nonwoven fabrics are made of differing basic weights. A total of one to three layers of polyester nonwoven fabrics serve as the cover sheets of the sandwiches, while a thermoplastic polyurethane grid serves as the interlayer in order to obtain different thicknesses. The buffering sandwiches are tested for bursting strength, air permeability, resilience rate, limited oxygen index, and drop-weight impact test, thereby characterizing their mechanical properties and buffering efficacy. The buffering sandwiches have an optimal residual impact stress of 4762 N when the polyester nonwoven fabrics have a basic weight of 150 g/m2. Moreover, the buffering sandwiches have an optimal resilient rate of 41.8% when they are composed of three-layered polyester cover sheets on both upper and lower sides, and are industrial product that qualified for use as buffering packaging.

Fiber-reinforced plastic (FRP) composites are widely used in engineering because of their high strength and light weight in comparison to monolithic metal alloys. They are mostly used in laminate f...

The purpose of this research was to enhance the stab resistance of protective clothing material by developing a new high-density nonwoven structure. Ice picks often injure Japanese police officers due to the strict regulation of swords in the country. Consequently, this study was designed to improve stab resistance against ice picks. Most existing anti-stab protective clothing research has focused on various fabrics impregnated with resin, an approach that brings with it problems of high cost and complicated processing. Seldom has research addressed the potential for improving stab resistance by using nonwoven structures, which exhibit better stab resistance than fabric. In this research, we prepared a series of nonwoven structures with densities ranging from about 0.14 g/cm3 to 0.46 g/cm3 by varying the number of stacked layers of Kevlar/polyester nonwoven under a hot press. We then proposed two methods for producing such hot-press nonwovens: the multilayer hot-press method and the monolayer hot-press method. Stab resistance was evaluated according to NIJ Standard-0115.00. We also investigated the relationship among nonwoven density, stab resistance, and flexural rigidity, and here we discuss the respective properties of the two proposed methods. Our results show that stab resistance and flexural rigidity increase with nonwoven density, but flexural rigidity of nonwovens prepared using the monolayer hot-press method only shows a slight change as nonwoven density increases. Though the two methods exhibit little difference in maximum load, the flexural rigidity of nonwovens prepared using the monolayer hot-press method is much lower, which contributes to superior wear comfort. Finally, we investigated the mechanism behind the stabbing process. Stabbing with an ice pick is a complicated process that involves many factors. Our findings indicate that nonwovens stop penetration primarily in two ways: nonwoven deformation and fiber fractures.

Sandwich-structure materials consist of a high-strength skin material and a lightweight core material. The advantages of sandwich structures are known to include excellent mechanical properties and low weight. Sandwich structures are lightweight because of their lightweight core; meanwhile, the skin structure provides mechanical strength and bears bending stress. Carbon-fiber-reinforced plastic (CFRP) is a high-specific-strength and high-specific-rigidity material. In recent years, CFRP sandwich structures have been used in aerospace applications due to their lightweight properties. However, soft-core members such as plastic foam materials have low rigidity and therefore may not exhibit adequate function as a sandwich structure. Webs can make up for the lack of rigidity of soft core members. Consequently, sandwich structures with reinforcement webs offer higher strength than sandwich structures without reinforcement webs. This study focused on reinforcement webs suitable for use in CFRP sandwich structure...

TiO2 nanoparticles were modified with 3-methacryloxypropyltrimethoxysilane (γ-MPS) and polyetherimide (PEI) in N-methyl-2-pyrrolidone (NMP) using an anchoring grafting method. The modified nanoparticles (TMP) were characterized using Fourier-transform infared spectra (FTIR), X-ray photoelectron spectroscopy (XPS), thermal gravimetric and differential thermal analysis (TG-DTA) and transmission electron microscopy (TEM), and were found to be successfully coated by γ-MPS and PEI layers. The dispersion-sedimentation mechanism that occurred in the modification of the TiO2 nanoparticles was examined and explained using a dispersion stability test. Nanocomposite films (TMP/PEI) that contained TMP nanoparticle as a filler material within a PEI matrix were also fabricated. Compared with traditional TiO2/PEI nanocomposite films, the TMP/PEI film exhibited improved tensile strength and tensile modulus, both before and after UV radiation.

With the development of technology, fibers and textiles are no longer exclusive for the use of clothing and decoration. Protective products made of high-strength and high-modulus fibers have been commonly used in different fields. When exceeding the service life, the protective products also need to be replaced. This study proposes a highly efficient recycling and manufacturing design to create more added values for the waste materials. With a premise of minimized damage to fibers, the recycled selvage made of high strength PET fibers are reclaimed to yield high performance staple fibers at a low production cost. A large amount of recycled fibers are made into matrices with an attempt to decrease the consumption of new materials, while the combination of diverse plain woven fabrics reinforces hybrid-fabric fibrous planks. First, with the aid of machines, recycled high strength PET fibers are processed into staple fibers. Using a nonwoven process, low melting point polyester (LMPET) fibers and PET staple fibers are made into PET matrices. Next, the matrices and different woven fabrics are combined in order to form hybrid-fabric fibrous planks. The test results indicate that both of the PET matrices and fibrous planks have good mechanical properties. In particular, the fibrous planks yield diverse stab resistances from nonwoven and woven fabrics, and thus have greater stab performance.

This study proposes fabric composites with improved static and dynamic puncture via increasing a friction force to restrain the slide of filaments as well as the compression and abrasion between the fibers and the puncture probe. The the bi-layered shell layers of composite fabrics are composed of aramid staple fibers and nylon staple fibers and a layer of low-melting-point polyester (LPET). The nonwoven layer consisting of recycled aramid and nylon staple fibers provides a shear effect to dissipate part of the puncture energy. Reinforcing interlayers include a woven fabric and PET filaments that are circularly aggregated between the surface layers, providing isotropic filament reinforcement and strengthening the resistance against the tip of the puncture probe. The reinforcing filaments may slide after the employment of needle punching, and to compensate for this disadvantage, the LPET layers are used to thermal bond the composite fabrics and the total thickness is controlled at 2 mm. The thermally bonded fabric composites are evaluated in terms of puncture resistance, thereby examining the effects of fabric structure and thermal bonding. According to the test results, the optimal composite structure is the sample N/L/W/F/L/N, which was reinforced by the LPET adhesive layer and irregularly aligned filaments. The sample which used the LPET adhesive layer had a positive influence on static puncture resistance and dynamic puncture resistance, preventing the slide of filaments, but the poor interfacial combination only contributed to limited reinforcement.

In this work, a new structural hybrid fabric reinforced polyetherimide composite was prepared using a solution impregnation method. The effects of fabric orientation, i.e., the angle between the projected line of the impact path of the solid particle on the specimen surface and the axis of the polybenzoxazole (PBO) fibers, and weft density on the erosion behavior of the prepared hybrid composites were investigated. The results show that the erosion rates of the hybrid composites decreased with increasing fabric orientation angle and weft density. No obvious crimp of carbon fibers was observed in the cross-section of a hybrid fabric prepreg sheet, therefore composites with excellent mechanical properties can be obtained. The carbon fibers were covered with PBO fibers and resin, and these protect the carbon fibers from damage well. The prepared hybrid composites showed better erosion resistance than carbon fiber reinforced thermoplastics and better mechanical properties than PBO fiber reinforced thermoplastics. Dynamic mechanical analysis showed that the prepared hybrid composite has high heat resistance.

How composites reinforced with plain-weave polybenzoxazole (PBO) fibers were eroded by solid particles was investigated. By evaluating the erosion rates of plain polymers and these composites at various impact angles ( α =15–90°), we confirmed that the polymers and their composites were ductile. The relationship between erosion behavior and fabric orientation from an energy perspective was studied, and our experimental results agreed well with our analytical results showing that the erosion behavior did not depend on fabric orientation. Using these results and scanning electron micrographs, a mathematical model was produced and it was used to predict the erosion rates of ductile materials. To verify this model, the theoretical and measured erosion rates of three high-performance ductile-fabric-reinforced thermoplastic composites were compared, showing that our mathematical model can accurately characterize their erosion behaviors.

In recent years, the excess amount of disposable plastic wastes has gained a concern for the environment. Polypropylene (PP) and thermoplastic polyurethane (TTPU) are both materials that can be properly heated to reform and reuse due to the inherent characteristics of thermoplastic materials. However, the using efficacy may be compromised as the waste may be overheating and thus damaged during the reheating process. Additionally, PP and TTPU are incompatible and immiscible, for which a compatibilizer - polypropylene grafted maleic anhydride (MA) was used. Hence, this study goals to investigate the synergistic effect between these materials and also discuss the compatibilized effect caused by MA. The thermal degradation behavior, melting and crystallization behaviors, and surface morphology of PP/MA/TTPU blends are evaluated under appropriate considerations. In light of the thermal degradation, the presence of thermally stable PP improves the thermal stability of TTPU accordingly. From TGA and DTG results, the addition of MA is also helpful, and therefore the third thermal degradation temperature (T3max) is increased by 5 °C averagely when compare to neat PP. T1max and T3max of PP/MA/TTPU are postponed about 2 and 4 °C when TTPU content varied from 10 to 30 wt%. SEM images show that the employment of TTPU strengthens the toughness of the surface, and with the aid of 5 wt% MA, PP and TTPU exhibit greater interfacial compatibility and better adhesion. Above all, this study aims to investigate the feasibility of using thermoplastic based on the consideration of how to sustain the excess plastic products and develop the measure to melt-blend diverse thermoplastics for reclamation. The excessive plastics via an easy and convenient melt extrusion process is expected to be regarded as an eco-friendly method for green development on mother earth.

A novel manufacturing technique called long-fiber-reinforced thermoplastic (LFT) is proposed to produce continuous flexible composite carbon fibers and fabrics. During the process, a polyester hot-melt adhesive (MPTU) is added to thermoplastic polyurethane (TPU) to form TPU blends that can improve the interfacial-bonding level. The TPU blends are extruded to enwrap carbon fibers and form an outer layer. The effects of the TPU blends on the composite are examined to determine the optimal parameters. At a TPU/MPTU ratio of 85/15 wt%, the blend exhibits good miscibility and the fiber tows show the optimal cluster effect and knot properties. Consequently, the specific strength of the optimal composite carbon fibers reaches 349.27 MPa·g−1·cm3. The resulting of composite carbon fabrics shows flexibility, and an average electromagnetic-interference shielding efficiency of 28.35 dB. Overall, this study reveals that LFT technique is an effective and novel method of developing carbon fiber-reinforced thermoplastics.

A polyetherimide (PEI) nanoparticle coating was prepared on carbon fiber (CF) surface by an evaporation induced surface modification, which was confirmed by scanning electron microscopy and Fourier-transform infrared spectrometer. The PEI nanoparticles were not perfectly spherical, but were pie shaped as observed by field emission scanning electron microscopy. Thus, the PEI nanoparticles were adsorbed on the CF surface instead of accumulating on the CF surface. To understand the effect of PEI nanoparticles on the interfacial shear strength between CF and thermoplastic resins, CF with a PEI nanoparticle coating was heated to melt the PEI nanoparticles. In addition to the desized CF, these three samples were used as reinforcements and some widely used engineering thermoplastic resins. The single filament fragmentation test was employed to assess the interfacial shear strength with an improved sample preparation process. The results show that the introduction of PEI coating increased the interfacial shear strength between CF and the thermoplastic resins mentioned above, especially the surface of the PEI coating used a nanoparticle morphology. In combination with the hot-bonding experiments, the compatibility of thermoplastic resins and PEI coating was shown to influence interfacial shear strength, but it was not the main factor.