Poly P-phenylene Terephthamide Research Articles

Poly‐p‐phenylene terephthamide modified poly(1,3,4‐oxadiazole) fibers with superior ultraviolet resistance

AbstractPoly‐p‐phenylene‐(1,3,4‐oxadiazole) (POD) fibers have attracted tremendous attention due to the excellent thermal stability, however, their poor ultraviolet (UV) resistance seriously restricted the application. Some efforts have been devoted to improving the UV stability of POD, while the methods are generally too complicated or costly. This work applied a simple but effective approach to obtain POD/PPTA composite fibers by blending poly‐p‐phenylene terephthamide (PPTA) with POD. The results showed that the obtained POD/PPTA composite fibers exhibited enhanced tensile strength and heat resistance compared to the pure POD fibers. The POD/10%PPTA composite fibers retained 68% strength and 43% elongation even after 24 h UV accelerated aging. The improvement of UV resistance was attributed to the photoinduced electron transfer reaction in POD/PPTA composite fibers, which has been demonstrated by both experimental and simulation studies.

Tribological properties of graphene oxide reinforced PPTA/PTFE composites

The tribological properties of the self-lubricating polymer were improved by strengthening the properties of the transfer film. The graphene oxide (GO) reinforced polytetrafluoroethylene (PTFE)/poly-p-phenylene terephthamide (PPTA) composites (GPPs) were prepared by dual-size synthesis. The tribological properties of GPPs were studied on a ball-on-disk tribometer. GPPs have low friction coefficient (minimum = 0.061) and hydrophobicity (maximum = 137.1385°). The structure–property relationships and the practical effect of transfer film enhancement induced by GO were revealed. We attempt to provide guidance for the GO reinforced self - lubricating polymers design. Finally, in light of the excellent properties of GPPs, this study provides guidance for the GO reinforced self - lubricating polymers design.

Preparation of silver nanoparticle functionalized aramid fiber by employing dopamine and silane coupling agent modification

AbstractSilver nanoparticles functionalized poly‐p‐phenylene terephthamide (PPTA) fiber was fabricated through the electroless plating method. To facilitate the efficient deposition of silver nanoparticles, the PPTA fiber surface was modified by using dopamine and γ‐methacryloxypropyl trimethoxy silane (MPTES). Various techniques including scanning electron microscope (SEM), X‐ray photoelectron spectroscopy (XPS) and X‐ray diffraction (XRD) were used to characterize the surface morphology and chemical composition of surface modified and silver‐plated PPTA fibers. The silver‐plated PPTA fiber showed a surface resistance of 0.53 Ω over a length of 1 cm with reliable coating fastness under ultrasonic washing and high temperature treatment. Furthermore, the silver‐plated PPTA fiber exhibited antibacterial resistance against Escherichia coli and Staphylococcus aureus, as well as good electrical heating performance with surface temperature of 100.4°C at a voltage of 4.5 V.

Chemical recycling of waste poly-p-phenylene terephthamide via selective cleavage of amide bonds catalyzed by strong Brönsted base in alcohols.

Poly-p-phenylene terephthamide (PPTA) is widely applied in bulletproof products and composite materials because of its high strength, high modulus, high temperature resistance and creep resistance. The PPTA molecule with highly symmetrical and regular structure is linear structure formed by the alternating connection of benzene ring and amide bond, and the amide bonds between the molecular chains form strong hydrogen bonds. Therefore, the dissolution and depolymerization of PPTA is very challenging. In this work, an efficient catalytic system was developed for the controllable degradation of waste PPTA, and the high-value added monomers terephthalic acid (TPA) and p-phenylenediamine (PPD) were recovered. The results show that the amide bonds of PPTA can be selectively cleaved by the strong Brönsted base catalysts in alcohols, especially in the NaOH/n-butanol system. Under the optimal degradation conditions (5wt% NaOH in n-butanol, 180°C, 6h), the percentage degradation of PPTA is 100%, and the yields of TPA and PPD are 92.0% and 91.5%, respectively. In addition, it is found that the wettability of n-alcohols on PPTA monofilament and the addition of a small amount of water have important influences on the degradation of PPTA. The work elucidates the degradation mechanism of PPTA, and reveals the important factors affecting the depolymerization of PPTA.

A phase separation method toward PPTA–polypropylene nanocomposite separator for safe lithium ion batteries

ABSTRACTThe building of separators with high thermal stability and security is important for lithium ion batteries. A novel, simple and successive process, which aims at coating poly‐p‐phenylene terephthamide (PPTA) onto commercial polypropylene (PP) separators, has been demonstrated. Without any additional binder, the PPTA nanofiber coating layer sticks to the porous PP separators by physical anchoring, endowing the composite separators with modified wettability toward electrolytes and heat resistance. Meanwhile, migration routes for lithium ions are guaranteed by the porous structure controlled by the self‐assembly of the fibrillar units during the nonsolvent induced phase separation. The cells equipped with the composite separators show better cycling performances. Moreover, the system based on the composite separators shows a sharp drop in ion conductivity after heat treatment at 200 °C for a certain period, indicating the shutdown effect of the composite separators, which can contribute to additional safety of lithium ion batteries. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 134, 46697

Finite-element Simulation of Kevlar Yarns and Fabrics in Assessing its Mechanical Protective Performance under Projectile Impact Loading

With the increasing concern on occupational safety, people pay more and more attention to mechanical protection. At present, the focus of relevant researches is on the mechanical protection performance of high-performance fibres and high-strength fabrics. The influences that mechanical properties of fabrics have on the mechanical protective performance of clothing are discussed in this paper. Woven fabrics made of high-performance fibres have been widely used as mechanical protective clothing in the form of flexible armour such as bullet-proof vests, stab-resistant garments and so on. The mechanical response and energy absorption characteristics of fabrics under high-speed projectile impact are dependent upon intrinsic constitutive relations, construction parameters such as fabric type, fabric construction, areal density, projectile shape, and impact conditions such as impact velocity and boundary conditions.This project involves the study of Kevlar fibre which is a poly-p-phenylene terephthamide (PPTA) fibre. The Kevlar fabric studied in this paper is plain woven. Experiments about construction parameters of Kevlar yarns are proposed to obtain the mechanical properties of woven fabrics. This paper also investigates the finite-element simulation of huge impact on Kevlar fabric by proposing a material model, which incorporates stretch and elasticity restoring property and failure criteria. A non-linear, explicit, three- dimensional finite-element program ANSYS is used to simulate the response of fabric to high-speed projectile impact with two Hookean springs and a Newtonian dashpot.