All-Aramid Composites by Partial Fiber Dissolution

Abstract

The area of self-reinforced polymer composites is one of the fastest growing areas in engineering polymers, but until now these materials have been mainly developed on the basis of thermoplastic fibers of moderate performance. In this work, we report on a new type of self-reinforced composites based on high-performance aramid fibers to produce an "all-aramid" composite by applying a surface-dissolution method to fuse poly(p-phenylene terephthalamide) (PPTA) fibers together. After immersion in concentrated (95%) sulphuric acid (H(2)SO(4)) for a selected period of time, partially dissolved fiber surfaces were converted into a PPTA interphase or matrix phase. Following extraction of H(2)SO(4) and drying, a consolidated all-aramid composite was formed. The structure, mechanical- and thermal properties of these single-polymer composites were investigated. Optimum processing conditions resulted in unidirectional composites of high reinforcement content (approximately 75 vol %) and good interfacial bonding. The all-aramid composites featured a Young's modulus of approximately 65 GPa at room temperature, and a tensile strength of 1.4 GPa, which are comparable with or exceed the corresponding values of conventional aramid/epoxy composites. However, since fiber, matrix and interphase in all-aramid composites are based on the same high-temperature resistant PPTA polymer, a high modulus of approximately 50 GPa was maintained up to 250 degrees C, demonstrating the potential of these materials for high-temperature applications.

High-performance electrospun co-polyimide nanofibers

“…The toughness of our high performance BPO nanofibers approaches Kevlar® 49 fiber, which is commonly used for anti-ballistic applications [25]. Although the BPO nanofibers have lower toughness than spider silk they have favourable levels of strength and stiffness, properties required for advanced composite applications.…”

Influence of corona discharge on the surface and thermal properties of aramid fabrics

“…Meta‐aramids (eg., NewStar®) and para‐aramids (eg., Kevlar®), thanks to their chemical structure, can form macromolecular chains that interact with each other due to the strong hydrogen bonding . The studies of the aramid textiles were focused mainly to determine their structural, mechanical, and thermal properties . The aramid surface is smooth, and they do not have active groups that can form covalent bonds with the applied coating.…”

Non-destructive characterisation of all-polypropylene composites using small angle X-ray scattering and polarized Raman spectroscopy

“…The highperformance polymer fibres can be embedded in a matrix polymer by film-stacking [1] or co-extrusion technologies [2,3] serving as suitable reinforcing substances and creating an SRP composite material with low density, enhanced strength, stiffness and impact resistance compared to the unreinforced polymer [4]. By selective melting via hot-compaction [5] or partial dissolution of the skins [6] of the polymer fibres to form the matrix phase, so called single-polymer composites can be created [7]. During production of self-reinforced composites, there are various parameters influencing the properties of the finally formed composite.…”