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Over the course of many years of use, impingement wear from dust, sand, and other materials can damage wind turbine blades, necessitating repairs and other maintenance work. Recently, wind turbine operators are turning to protective films, which allow such work to be completed more efficiently, as an alternative to the conventional approach of using paint to repair wind turbine blades. However, the erosion resistance characteristics of repaired blades remain unclear. In this study, we create paint- and protective film-coated samples to reproduce repairs, measure their erosion resistance, and study underlying factors in an effort to verify the erosion resistance of repaired materials and associated mechanisms. The low erosion resistance of GFRP can be significantly improved by applying a protective film made of a ductile material. Such material effectively protects the surface of the GFRP. Moreover, the erosion resistance of protective films made from polyurethane material is superior to that of paint. We recommend use of protective film with wind turbine blades when manufacturing blades and regular maintenance. [ABSTRACT FROM AUTHOR]

In this study, impact-resistant polypropylene (MPP), thermoplastic polyurethane (TPU) and polypropylene-grafted maleic anhydride (MA) are made into MPP/TPU/MA blends using melt-compounding and injection methods. The blending morphology, crystallization behavior, and melting and thermal behaviors of the blends are evaluated in terms of the content of TPU and MA, examining the influences of the parameters. The scanning electron microscope (SEM) observation shows that 1 wt% of MA can effectively enhance the interfacial adhesion and compatibility between MPP and TPU. The differential scanning calorimetry (DSC) results show that the crystallization temperature and melting temperature of the blends are not dependent on the content of TPU or MA. However, using TPU and MA adversely affect the crystalline and melting enthalpy of the blends. The thermogravimetric analysis (TGA) and derivative thermogravimetry (DTG) curve both show that the higher the MPP, the greater the thermal stability of TPU. Likewise, using MA as compatibilizer also has a positive influence on the thermal stability of the blends. The X-ray diffraction (XRD) analyses confirm that the addition of TPU decreases the diffraction intensity of MPP, but does not harm the crystalline structure of MPP. Moreover, the addition of MA improves the compatibility between MPP and TPU. MA marginally decreases the peak value and does not influence the crystallinity degree of MPP. It is expected that the results of SEM, DSC, TGA, DTG, and XRD can serve as a valuable reference for the design of composites with improved thermal and crystallization behaviors. Keywords: Impact-resistant polypropylene, Thermoplastic polyurethane, Maleic anhydride, Thermogravimetric analysis, Derivative thermogravimetry, Blends, Crystallization

Carbon fiber reinforced plastics (CFRPs) are widely used in the aerospace, automotive, and construction industries. CFRP prepregs (intermediate products) are generally used in CFRP production, with a large number of prepreg cut‐offs being discarded during cutting processes. There is strong demand for a method for recycling carbon fiber prepreg cut‐offs. This paper proposes a method for recycling such material, which is characterized by low cost and high added value, in order to foster the development of a recycling‐oriented society. We prepare carbon tapes (CTs) by cutting discarded cut‐offs according to their size so as to maximize fiber length. Using a simple water CT dispersion method, we fabricate uniform CT sheets and mold a recycled CT‐reinforced composite (R‐CT‐RC). Sample prototyping and mechanical characteristic testing indicate that this R‐CT‐RC is characterized by low recycling cost and desirable mechanical properties. Recycled CT‐reinforced composite with thermoplastic (R‐CT‐RC/TP), which is prepared by adding thermoplastic resin between CTs, can be re‐molded and therefore readily re‐recycled. [ABSTRACT FROM AUTHOR]

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 ( α y and α f ) 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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

With high specific strength, carbon fiber reinforced plastic (CFRP) is used in many fields. Repair is necessary when the strength of the leading edges of aircraft wings (CFRP) and wind power turbine blades (CFRP) are damaged by lightning strikes or collisions with birds. Some studies have been conducted on the mechanical properties of repair methods, but they do not address erosion characteristics. In order to develop a high quality repair method, this study examined the repair patch and fabricating samples that reproduces the conditions associated with the current repair method, the erosion characteristics of the sample were investigated using the erosion test. Differences in the adhesive used to affix the repair patch to the base plate have little effect on the erosion resistance of repaired areas, but deteriorations in adhesion between the repair patch and base plate result in degraded erosion resistance in the repaired area. With regard to the mechanism by which post-repair erosion resistance characteristics changed, our tests revealed that adhesive irregularities between the repair patch and base plate allowed impact energy from particle collisions to cause the repair patch to vibrate, and the resulting fatigue breakdown caused resin and fiber fragments to more readily separate, accelerating erosion. [ABSTRACT FROM AUTHOR]

Extrusion is employed to combine carbon fiber tows and thermoplastic polyurethane (TPU) blend. TPU‐cladded carbon fibers undergo knitting to form carbon fiber knitted composites. Microscopic observation proves that the compound carbon fibers are composed of a double‐layered structure with interfacial bonding and fiber axial alignment. In addition, the TPU coating can reduce friction during knitting, which provides the carbon fiber knitted composites with flexibility and resilience. Regarding the mechanical properties, the tensile strength is in direct proportion to the number of lamination layers. In particular, six‐layered knitted composites exhibit an optimal tensile strength of 43.72 MPa, whereas four‐layered knitted composites exhibit optimal tensile elongation. Through the manufacturing and evaluations in this study, continuous carbon fibers can be fabricated via extrusion, thereby obtaining a knitted structure that can be laminated to strengthen the mechanical properties and electromagnetic interference shielding efficacy of the laminated composites. Large composites can also be achieved, which overcomes the limits of continuous carbon fibers in subsequent production. © 2021 Society of Industrial Chemistry. [ABSTRACT FROM AUTHOR]

We have proposed the filament cover method for fabricating carbon fiber-reinforced plastic (CFRP) with high axial compression characteristics to address one of the shortcomings of unidirectional CFRP, whose compressive strength is inferior to its tensile strength. In this paper, we attempt to fabricate CFRP with high compressive strength while retaining the high tensile strength of unidirectional CFRP. We propose a method for surface modification of sheath filament PBO ねber (corona discharge treatment followed by silane coupling treatment) and a method for increasing the reinforcing fiber volume fraction of CFRP (flattening reinforcing fiber bundles and shrinking the gaps between them). CFRP prototypes fabricated using them exhibit tensile strength on par with regular CFRP, the effectiveness of the method was confirmed. [ABSTRACT FROM AUTHOR]

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%. [ABSTRACT FROM AUTHOR]

Long molding times and the impossibility of remelting or reforming carbon fiber-reinforced plastics (CFRPs) that contain thermosetting resin after molding have led researchers to focus on carbon fiber-reinforced thermoplastics (CFRTPs) made with thermoplastic resin. Compared to CFRPs, CFRTPs are easier to recycle, but they generally exhibit strength properties that are inferior to those of CFRPs due to poor adhesion between the carbon fiber and the resin. To address this issue, we devised a new surface modification method (using a titania solution) to improve adhesion between fiber and the resin. Fragmentation and tensile tests were used to evaluate the effect of the surface modification method on CFRTP adhesion. The results indicate that surface modification can enhance adhesion in CFRTP, which may improve the material's mechanical properties. [ABSTRACT FROM AUTHOR]

In this study, long fiber‐reinforced thermoplastics (LFT) and coextrusion are applied to wrap carbon fiber tows in a thermoplastic polyurethane (TPU) outer layer. In this way, the proposed wrapped yarns have a sheath–core structure. Scanning electron microscopy observation reveals that TPU and carbon fiber tows form a physical combination that allows TPU to further enhance the tensile strength of carbon fiber tows by 35.87%, which is 19.62 ± 1.88 MPa. The tensile strain of carbon fiber tows also improves. LFT and coextrusion are performed to produce successive carbon fiber tows that can be successfully fabricated into textiles, possessing good fabric flexibility. The technique of carbon fiber tows can be applied to mass production feasibility for the field of carbon fiber composites. [ABSTRACT FROM AUTHOR]

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, the latter of which is the result of a lightweight core. However, soft‐core members such as plastic foam materials have low rigidity and therefore may not exhibit adequate functionality when used in sandwich structures. This research sought to reduce environmental impact and to facilitate sustainable development by developing a method for fabricating high‐strength carbon foam using alkali lignin for use as an FRP sandwich core and enhancing the mechanical properties of the carbon foam with short glass fiber. PMMA particles decomposed at high temperatures to leave gaps, creating carbon foam with a closed structure. The relationship between PMMA particle size and foam pore size was investigated by observing cross‐sections of the foam. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

In Japan, where a safe and secure society has been established, stab proof clothing that are suitable for police and security officers supporting are required. So far, most of the stab-proof clothing is made of the metal plate or thick multi-layered fabric with high-strength fibers. It is commonly used as a stab-proof vest because it cannot cope with the large deformations, which caused by the joints such as arms or neck. This research aims to develop high flexible stab-proof clothing that can be applied in large-deformation part such as joints with high stab-proof performance. We developed a testing device that can measure bending characteristics under the same conditions as when the stab proof clothing is actually worn on the human body. The usefulness of the evaluation method was confirmed. And the factors that affect the bendability of the elbow joint were also be studied. The mechanical properties of the material and the gap between the arm and the cylindrical structure are greatly affected, and the effect of each bending angle on the bending moment is different. We considered the deformation of the material when it bending and then proposed a new stab-resistant material structure and trial production. The cylindrical bending test shows that the flexibility of the new structure is greatly improved. [ABSTRACT FROM AUTHOR]

Featured Application: The ultimate purpose of this study is to treat waste compounds via a simple hot-pressing approach to produce useful materials that can be used again. As a result, this study attenuates the negative influences of plastic waste on the environment while achieving sustainable development. With appropriate conditions, thermoplastic materials possess a good reversible ability. They are prone to exceed the reversibility range when being repeatedly processed as they cannot bear high temperatures. Therefore, this study aims to explore the impacts of the melting–recycling cycles and the presence of a compatibilizer on the omnipresent thermoplastic materials. Additionally, the tensile properties, morphology, and thermal properties are studied. The feasibility of multiple utilizations and differentiation effects are examined afterward. In this study, recycled or mechanically damaged thermoplastic polyurethane (T)/polypropylene (P) waste blends are used as the raw materials for the hot-pressing cycle, while maleic anhydride grafted polypropylene (MA) is used as the compatibilizer, thereby simulating the waste compounds. Next, the T/P/MA blends that undergo post-2nd and post-3rd recycling are evaluated for comprehensive change. The test results indicate that without MA, T/P blends exhibit significant differentiation effects due to an increase in the polypropylene content and multiple melting–recycling cycles. By contrast, the presence of MA mitigates the overall differentiation effect of T/P blends. The ultimate purpose of this study is to treat waste compounds via a simple hot-pressing approach to produce useful materials that can be used again. As a result, this study attenuates the negative influences of plastic waste on the environment while achieving sustainable development. [ABSTRACT FROM AUTHOR]

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 compression side. Because FRP has low compressive strength in the axial direction, the shell's compression side fails first, making it necessary to sacrifice the material's tension characteristics and to use more material that would otherwise be necessary when designing structures. This article describes (a) a propose the filament cover method for wrapping filament around the reinforcing fibers in unidirectionally FRP as a way to improve the material's bending strength, (b) molding of FRP using prototype reinforcing fiber bundles, and (c) evaluation of the material's compression and bending characteristics. Results indicate that FRP molded into filament-covered carbon fiber bundles exhibits significantly better compression characteristics than conventional CFRP as well as high bending strength, indicating the effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]

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 dangers that lurk anywhere anytime. People are concerned about safety and have increasing demands on self-protection in terms of working/living environment, accidents, and raising crime rates. The increasing demands of protective textiles cause the mass production of high performance fabrics, leaving considerable amount of high performance selvages. In this study, three kinds of high performance recycled selvages, including Nomex, Kevlar, and PET selvages, are used to make high-performance hybrid composites. The recycled selvages are smashed into staple fibers using a nonwoven manufacturing process. Each recycled staple fibers are individually combined with low-melting-point polyester (LPET) fibers at ratios of 9:1, 7:3, and 5:5, and processed with thermal compression. The LPET fibers contribute to the hybrid composites with thermal bonding points, which decrease the voids between fibers, limit the fiber slide, and enhance the friction force between fibers. The shearing, expelling, and friction functionalities of LPET fibers are expected have a positive influence on the mechanical properties of the high-performance hybrid composites. The morphology of hybrid composites is observed using a scanning electron microscope, and the air permeability, tensile strength, tearing strength, and bursting strength of hybrid composites are evaluated, examining the optimal parameters. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Portable devices are among the products made from fiber-reinforced plastic (FRP), which is characterized by high strength and low weight. The molding method for small devices involves use of flat sheets, but use of such methods for structures with highly curved corners, for example portable devices with right angles, either results in wrinkles or requires that the FRP be cut into pieces, introducing discontinuities where failure is more likely to occur. This issue results when structures with highly curved corners are made using flat fabric, and it can be solved by creating a threedimensional fabric. This study proposes a new method for manufacturing three-dimensional fabric to cover highly curved corners and edges. The authors also carried out a four-point bending test of the edge portion of such fabric based on the method described in ASTM D 6435. The result is a new molding method for three-dimensional fabric FRP that promises to play a more useful role than conventional molding processes in manufacturing future portable devices. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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 form and are stronger within layers than between layers, making them prone to cracking and peeling. This type of structural degradation can be dangerous during operation. For this reason, research on FRP composites with the ability to self-repair has attracted much attention. In this study, we developed a new method to repair glass fiber-reinforced plastic (GFRP) composites by using ultraviolet-(UV) cured resin. As GFRP composites are UV transmissive, the repair process can be carried out externally by exposing the damaged part to UV light. The transmittance of EP GFRP is about 40%. Holes were pre-drilled with wires in order to facilitate the injection of UV resin between the layers of the composite, and this process was accomplished without degrading the mechanical properties of the material. A double cantilever beam (DCB) test was performed on the GFRP composite to induce interlaminar fracturing. UV-curable resin was then injected between the layers of the composite through a series of pre-drilled holes. Following this repair, the DCB test was performed again to evaluate the repair rate. A compressive after impact (CAI) test was also performed on the GFRP composite to induce delamination. Compressive strength before and after the repair was also evaluated. [ABSTRACT FROM AUTHOR]

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 structures by evaluating the bending characteristics of CFRP sandwich structures with reinforcement webs. Experimental results demonstrated that CFRP sandwich structures with reinforcement webs had improved bending strength. The effects of the spacing interval of reinforcement webs and the number of layers of carbon fiber fabric on the bending characteristics of CFRP sandwich structures were also examined. Finally, an optimal condition model was created for CFRP sandwich structures with reinforcement webs. [ABSTRACT FROM AUTHOR]

The effects of covering ultra‐high molecular weight polyethylene (UHMWPE) fibers with different types and spacings of filaments on the longitudinal compression properties of unidirectional UHMWPE fiber‐reinforced epoxy resin samples were investigated. UHMWPE fiber bundles covered with fiber filaments were prepared using a custom winding machine, and composites were subsequently fabricated by vacuum‐assisted resin transfer molding. Covering filament spacing was controlled by the warp speed. Compression testing of the resulting samples was performed and the fracture surfaces were examined by an optical microscope. The results showed that the compression strength and modulus of the unidirectional composites reinforced with filament‐covered bundles depended strongly on the compressive failure mechanism, which was decided by the type and spacing of the covering filament. Four kinds of filaments have positive effect for compressive properties of composites, for the basalt filament, the effect for improving compressive strength is best, the improving percentage is 18.4%. For the UHMWP and PBO filament‐covered UFRPs displayed considerable increases of compressive modulus, with improvements of about 36% and 45%. POLYM. COMPOS., 39:247–253, 2018. © 2016 Society of Plastics Engineers [ABSTRACT FROM AUTHOR]

In the present article, a highly heat-resistant composite with a high fiber volume fraction (Vf > 60%) was successfully manufactured using engineering plastic Nylon66 as matrix and carbon fabric as reinforcement by a solution impregnation molding method. The mechanical properties of the composite were investigated using a tensile measuring device. Mechanical analysis revealed the superior mechanical properties of the composite relative to those of previously reported carbon fiber-reinforced thermoplastics (CFRTPs). The cross section and fracture surface of the composite were characterized by scanning electron microscopy. The resin successfully impregnated the fiber bundles and the bonding strength of the fiber–resin interface was excellent. Dynamic mechanical analysis was used to evaluate the heat-resistant property of the composite. The composite exhibited a better heat-resistant property relative to that of the carbon fiber-reinforced crystalline co-polyester composite. To further verify the versatility of this method, super engineering plastic polyetherimide with a higher molecular weight was successfully employed as matrix to prepare CFRTP. [ABSTRACT FROM AUTHOR]

Most stab-proof vests in use are made from metal plates, whose weight, bulk, and rigidity make them unsuitable for use over extended periods of time• し ight, thin, and flexible clothing that protects against knives and other sharp objects is needed. However, achieving high levels of puncture resistance and comfort remains a challenge. While plain textiles can resist slashing, they cannot withstand stabbing. In this study, we investigated the stab resistance of aramid fabrics impregnated with micro-glass particles and nano-silica particles and evaluated the influence of particle size and mass concentration by measuring the load, displacement, and energy when the samples were struck by a blade. Particle-impregnated rabncs showed good puncture resistance. The smaller the diameter of the particles, the greater the material's resistance to penetration. Movement of yam strands is inhibited by impregnation with particles. Furthermore, the friction force acting on intersecting sections of plain fabric exhibits the largest influence on stab resistance. [ABSTRACT FROM AUTHOR]

Solid particle erosion in industrial applications has been a serious problem in many engineering fields. Earlier studies on fiber-reinforced plastic (FRP) composites were mainly focusing on the erosive wear behavior at several different impact angles. However, the effect of fiber orientation on FRP composites has not been thoroughly investigated. Since fiber orientation is one of the important factors in which causing erosive wear damages to FRP composites, in order to understand the virtue of this problem, it is important to investigate the effect of fiber orientation at different impact angles. In this research, the effect of fiber orientation of unidirectional fiber-reinforced plastic composites on erosive wear behavior was studied. Sandblasting-type erosion tests were conducted on the FRP composites with fiber orientation ranging at three impact angles to clarify the relation between fiber orientation and erosive wear behavior. The Dyneema fiber (ductile material) and the carbon fiber (brittle material) were used for the reinforcement fiber in FRP. From the result, it is confirmed that CFRP composites with higher fiber orientation angle erode faster than the composites with lower fiber orientation angle. But the erosion characteristic of DFRP was almost the same regardless of the fiber orientation angle. The damaged surfaces of the FRP composites were then analyzed using scanning electron microscopy and the possible erosion wear mechanisms were investigated. [ABSTRACT FROM AUTHOR]

A filament covering is proposed to improve the longitudinal compressive properties of unidirectional fiber reinforced plastic. Based on compressive buckling theory, fiber buckling can be prevented by shortening the buckling critical wavelength by covering the filament. In this paper, a UHMWPE fiber bundle and a PBO filament were selected as the reinforcing fiber and the covering filament, respectively, to verify this statement. The effect of a covering PBO filament on a UHMWPE fiber reinforced epoxy resin on compressive performance was investigated by a compressive test and morphology observations. Results show that the filament covering has positive effect on the compressive strength of the FRP, and the tension-exerted filament covering increased the compressive strength and increased the longitudinal compressive modulus of the UFRP. [ABSTRACT FROM AUTHOR]

In the present study, the tensile properties of a single ramie fiber and the adhesion of ramie and a resin were compared at 170, 180, 190, 200, 210 and 220 °C. The results revealed that the most suitable temperature for the formation of a unidirectional composite is 190 °C. The tensile properties of the non-woven ramie fiber fabric, woven ramie fiber fabric, ramie fiber yarns, or sliver reinforced composites were tested and compared, and their structures were analyzed by X-ray computed tomography. The results revealed that sliver was the most suitable reinforcing material for unidirectional composites. We also know that the tensile strength and tensile modulus increased as the fiber volume content increased, and the relationships between them were linear. [Display omitted] • Environmentally friendly and low-cost process. • Production of high strength green composites with natural materials. • Effect of fiber volume content on tensile strength of green composite. • Ramie fiber/cellulose resin green composites have good application potential. [ABSTRACT FROM AUTHOR]

In Japan, where a safe and secure society has been established, stab proof clothes that are suitable for police and security officers supporting are required. The current stab-protection clothing uses mainly metal plates, and there are various problems, such as weight and poor comfort. This study therefore seeks to improve the comfort of stabresistant clothing, clarify the mechanism of stab-resistant clothing, and optimize its structure to achieve low cost. The test equipment was developed in this study. We attached a knife to the tip of an air cylinder. This device penetrates a sample, and the load and displacement can be measured. A sharp instrument such as an ice pick penetrates a sample easily because it passes between the fibers of the textile. Therefore, we suggested using a textile with a nonwoven fabric structure so that the instrument would strike the fiber. Experiments revealed that non-woven fabric has considerably higher stab resistance than other fabrics. [ABSTRACT FROM AUTHOR]

CFRP has been applied in various fields where it is mostly used as laminates. CFRP laminates are likely to fracture between the interlaminar surfaces. To resolve this problem, we proposed a self-healing system for CFRP using optical fibers and UV-curable resin. In this study, self-healing CFRP samples were prepared and the effectiveness of repairing the inter-laminar fractures was confirmed by using optical fibers and UV-curable resin. In addition, we have also clarified the factors that affect the repair rate by determining the bonding strength of epoxy resin and UV-curable resin. From the experiment results, we were able to confirm the feasibility of the proposed self-healing system. [ABSTRACT FROM AUTHOR]

The influence of recycling on the impact damage resistance of recycled carbon fiber-reinforced polymer (CFRP) composites was investigated using low-velocity impact and compression after impact (CAI) tests. The relationships among load, force, and time were analyzed to gain insight into the damage characteristics of three types of composite laminate: virgin CF-reinforced polymer (V-CFRP), recycled CF-reinforced polymer (R-CFRP), and treated recycled CF-reinforced polymer (TR-CFRP). Special emphasis was placed on evaluating the extent of damage and the residual mechanical properties as affected by three different fiber surface states. Substantial differences were noted in the shape, area, and damage mode of impact using ultrasonic c-scanning, photography, and scanning electron microscopy (SEM). V-CFRP indicated significant improvement in impact damage resistance in the form of less damage, higher residual strength, and greater shear failure angle. Damage resistance was improved up to 80% of V-CFRP by surface cleaning while R-CFRP is 50% of V-CFRP. Shear failure angle of 16° was attained from R-CFRP and it was increased to 24° when the recycled fibers were cleaned. The result of SEM showed that there was less delamination of TR-CFRP compared with R-CFRP. This work proves that the low-velocity impact response of recycled composites can rival that of virgin composites, while providing a basis for future applications of recycled carbon in many fields. POLYM. COMPOS., 35:1494-1506, 2014. © 2013 Society of Plastics Engineers [ABSTRACT FROM AUTHOR]

In recent years, non-woven bag filters have been used in waste incinerators for efficient collection of dust and removal of detrimental gas. However, dust dislodgement efficiency decreases with time until the bag filters are no longer useable. Dust adhering to the fabric is a major determinant of bag filter life. In this study, a flat filter was used to study the relationship between various parameters of the bag Filters? structure and dust dislodgement efficiency. The results confirm that the filter density and the modulus of elasticity of baking fabric in bag filters affect the dust dislodgement efficiency of a bag filter. Higher filter density in a bag filter prevents dust from penetrating the filter, thus helping the filter to dislodge dust easily. The filter having high modulus of elasticity of backing fabric has a small displacement, and prevents the dust from penetrating the bag filter. The filter with the hybrid structure has been suggested, Filter with a hybrid structure has been suggested, its effectiveness has been confirmed for the improvement of dust dislodgement efficiency. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

In fiber-reinforced plastic materials, the fiber volume fraction is one of the most important parameters, and it strongly influences the composite properties. However, it is hard to improve impregnation and the fiber volume fraction in fiber-reinforced thermoplastics because thermoplastic resins have high melt viscosities. This study explored a reformative solution impregnation method for molding fabric-reinforced thermoplastic composites with a high fiber volume fraction. The fiber volume fraction was significantly increased, to 60%, which is equal to that of fiber-reinforced thermosetting plastic materials. A comparison indicated that a fiber-reinforced thermoplastic and a fiber-reinforced thermosetting plastic with the same reinforcing fiber had similar tensile properties and that the proposed molding method is effective in thermoplastic composite manufacture. POLYM. COMPOS., 34:953-958, 2013. © 2013 Society of Plastics Engineers [ABSTRACT FROM AUTHOR]