Jan-Yi Lin

Effects of needle-punching and thermo-bonding on mechanical and EMI shielding properties of puncture-resisting composites reinforced with fabrics

Effects of needle-punching and thermo-bonding on tensile property, air permeability, puncture resistances and EMI shielding effectiveness were discussed for carbon-reinforced composite and glass-reinforced composite. The result shows that, needle-punching significantly improves static and dynamic puncture resistances. As increase of needle-punched density, static and dynamic puncture resistances show firstly increasing and then decreasing trend. Thermo-bonding almost has no influence on static puncture resistance, but effectively decreases dynamic puncture resistance. Comparatively, carbon-reinforced composite shows higher static and dynamic puncture resistances than glass-reinforced composites when being needle-punched at 200 needles/cm2. Meanwhile, carbon-reinforced composite has superior EMI shielding effectiveness to 40–60 dB at frequency of above 1 GHz, reaching 99.99 % shielding efficacy.

Effect of Process Parameters on Puncture Resistance of Composites by Needle Punching and Thermal Bonding Techniques

This article presents the effect of process parameters on both static and puncture resistance properties of composites that were made of glass fabric and nonwovens through needle-punching and thermal bonding techniques. The experiments were conducted under varying process parameters, namely, low-Tm polyester content, needle-punched density, and nonwoven plied orientation and glass fabric angle. The significance of the process parameters is determined by analysis of variance (ANOVA). It is found that the needle-punched density and low-Tm polyester fiber content impact on the static puncture resistance interactively and significantly. Also, both nonwoven plied orientation as well as glass angle have effect on the dynamic puncture resistance, but only the former significantly influences the static puncture resistance.

Static and dynamic puncture failure behaviors of 3D needle-punched compound fabric based on Weibull distribution

Through-thickness reinforcement structure of compound fabric was formed through a two-sided needle-punching and thermal-bonding processes. This study presents static and dynamic puncture resistances of compound fabric comprised of Kevlar®/PA6/low-melting PET nonwoven, low-melting PET/PET nonwoven and woven fabric. The effect of the staple fibers fraction on puncture resistance was investigated to assess optimal fiber content in the nonwoven layer. Static and dynamic puncture failure models of non-thermal-bonded and thermal-bonded compound fabrics were constructed using a Weibull probability distribution to predict puncture failure reliability. Result indicates that puncture forces increased and then decreased with low-melting PET fibers, but steadily improved with recycled Kevlar® fibers. Puncture failure probability models show that thermal-bonding largely improved failure reliability of the static puncture property, but slightly decreased dynamic puncture performance. Puncture failure mechanisms were respectively exposed according to SEM observations.

Static and dynamic puncture properties of intra-/inter-laminar reinforced multilayer compound fabrics by needle-punching and thermal bonding

A new approach for intra-/inter-laminar reinforcement using needle-punching and thermal bonding was proposed for improvement of puncture resistance of multilayer compound fabrics that were composed of different kinds of nonwovens and woven fabrics. Effects of woven fabric orientation and thermal bonding on static and dynamic puncture properties were explored. Multilayer compound fabrics with different compositions of nonwoven and sequence of woven fabrics were comparatively discussed to confirm fabric and nonwoven influencing on static and dynamic puncture resistances. Puncture resistance mechanism of plied orientation and thermal bonding was analyzed for multilayer compound fabrics. The research result shows that woven fabric orientation affected static and dynamic puncture resistances more significantly when multilayer compound fabrics were comprised of high-modulus nonwovens and woven fabrics. Plied orientation correlated with the yarn density of woven fabric that was contained in compound fabrics. Contact length between woven fabric and nonwoven, as well as specific fiber toughness from nonwoven, was respectively responsible for static and dynamic puncture resistances of multilayer compound fabrics.

Mechanical and physical properties of puncture-resistance insole made of Kevlar® recycled selvages

The polyester (PET) fibers and Kevlar® staple fibers, which are recycled from discarded selvages of PET and Kevlar® woven fabrics, are made into nonwoven fabrics using a needle-bonded process. The PET/Kevlar® nonwoven matrices are used as the surface layers, while a glass fiber woven fabric is used as the interlayer. The sandwich-structured composites are saturated with waterborne PU resin and then hot pressed, forming puncture resistant PU-reinforced PET/Kevlar® sandwiches. The sandwiches are evaluated in terms of the tensile property test, the bursting property test, the constant-rate puncture test, the dynamic puncture test, and the drop-weight impact test. The test results indicate that increasing the pick-up rate of PU resin can significantly improve all mechanical properties, suggesting that PU-reinforced PET/Kevlar® sandwiches have protective functions and make good candidate for insoles.

Modeling and optimization of dynamic puncture behaviors for flexible inter-/intra- reinforced compound fabrics

In this article, the new model of dynamic puncture behaviors of intra-/inter- reinforced compound fabrics which are fabricated by nonwovens and reinforced fabrics using needle-punching and thermal bonding technique is constructed by the maximum deformation and stress-wave transmission theory. Moreover, the number of layers for E1 puncture protection is optimized based on numerical analysis of penetration depth. Dynamic puncture model shows that the dynamic puncture resistance depends on elastic modulus of reinforced fabrics, deformation radius and thickness of compound fabrics. The maximum puncture resistance and penetration depth both have parabola relations to number of layers. This study provides the accurate prediction model of puncture force and safety layers for designing puncture-resisting body armor in the future.

Biodegradable Polyvinyl Alcohol Vascular Stents: Structural Model and Mechanical and Biological Property Evaluation

This study proposes structural models of biodegradable vascular stents. One, two, or three plies of biodegradable polyvinyl alcohol (PVA) yarns are combined and twisted with twist factors of 2, 3, 4, 5, and 6 to form one-, two-, and three-ply PVA twisted yarns. The braided, warp-knitted, and weft-knitted PVA vascular stents are composed of PVA twisted yarns by using a braider, a warp knitting machine, and a weft knitting machine. The formation and mechanical properties of PVA vascular stents are evaluated, and the biological properties are examined in terms of biocompatibility through in vitro assay and subcutaneous embedding using in vivo assay. Test results indicate that the compression strength of PVA vascular stents is improved when using PVA twisted yarns containing a high number of plies and twist factor. Specifically, weft-knitted PVA vascular stents exhibit the optimal compression strength. PVA vascular stents treated with chemical cross-linking show weight loss lower than 3% after immersion in PBS solution for 30 days. Moreover, the antibacterial test and cell culture results suggest that PVA vascular stents are nontoxic and biocompatible. Subcutaneous embedding results show that PVA vascular stents retain intact formation when subcutaneously embedded in vivo for 28 days, indicating their good biological property. PVA vascular stents are suitable candidates for tissue engineering applications.

Manufacturing techniques and property evaluations of sandwich-structured composite materials with electromagnetic shielding, flame retardance, and far-infrared emissivity

This study aims to produce sandwich-structured composite boards with flame retardance, far-infrared emissivity, and electromagnetic shielding effectiveness using nonwoven, weaving processes, and heat treatment. Needle punching and roller-type hot pressing are used to improve their tensile strength, tensile elongation, puncture strength, and burst strength. The limiting oxygen index is 30 regardless of whether the flame retardance/far-infrared emissivity/electromagnetic shielding effectiveness composite board is stainless steel (SS), SS+Ni–Cu (nickel-coated copper), or SS+Ni–Cu+Cu (copper) composite fabrics. SS+Ni–Cu and SS+Ni–Cu+Cu composite boards both have optimal thermal conductivity at the eighth test hour. SS–B composite board exhibit far-infrared emissivity of 0.81; moreover, they have optimal electromagnetic shielding effectiveness of −41dB at 2450 MHz when they are laminated into three layers at a 90° lamination.

Plastic packaging materials of laminated composites made of polymer cover sheets and a nonwoven interlayer

This study aims to improve the mechanical properties, stabilized structures, and light weight plastic packaging materials to realize diverse applications. A sheet extrusion machine is used to fabricate sandwich-structured composites, which are composed of two polymer cover sheets and a nonwoven interlayer. The samples are prepared in two batches with different cover sheets: thermoplastic polyurethane and polypropylene. Moreover, low-melting-point polyester (LMPET) fibers and Kevlar fibers are fabricated into a LMPET/Kevlar nonwoven interlayer. The laminated composites are evaluated in terms of morphologies, mechanical properties, combustion rates, and thermal behavior. Kevlar fibers are flame resistant and mechanically strong. LMPET fibers promote the interfacial bonding between layers. Thus, the laminated composites are good candidates as packaging materials, and they can be made with rigid or soft materials, depending on specified requirements. Rigid materials can provide higher strengths, and the distribution of fibers thus helps the PP-based laminated composites to obtain higher crystal stability. Moreover, using TPU with flexibility contributes to high extensibility, which grants the laminated composites with high toughness, light weight, and low restriction against the morphology. Such manufacturing is also efficient and economical, thereby satisfying the requirements of plastic packaging materials.

Fabrication, properties, and failure of composite sandwiches made with sheet extrusion method

Fiber-reinforced polymer composites are commonly used in different fields because the evenly distributed fibers in polymer can efficiently transmit the load of a force and mechanically reinforce the polymer matrices. This study proposes producing composite sandwiches using thermoplastic polyurethane sheets as the top and bottom layers and a polypropylene/Kevlar nonwoven fabric the interlayer. Thermoplastic polyurethane sheets and a polypropylene/Kevlar nonwoven fabric are combined using the sheet extrusion method, during which the polypropylene staple fibers are melted and firmly bond the thermoplastic polyurethane sheets. The mechanical properties, thermal behavior, and surface morphology of composite sandwiches are evaluated, examining the influence of parameters. The test results show that the composite sandwiches are mechanically reinforced as a result of using the nonwoven covers. Moreover, the improved interfacial bonding between the cover layers and the interlayer inhibits delamination, and the stabilized structure subsequently decreases the level of combustion which is in conformity of the differential scanning calorimetry results. The manufacturing is creative and efficient due to one-step shaping, creating a refined composite sandwich with good mechanical properties and combustion resistance.