Mechanism of improvement in the strength of para-aramid paper by polyphenylene sulfide pulp

Aramid paper has been widely applied in aerospace, rail transit, and other fields because of its outstanding mechanical properties, high-temperature resistance, and excellent insulation. We prepared para-aramid chopped fibers/polyphenylene sulfide (ACFs/PPS) composite paper, which has superior mechanical strength compared with other aramid papers. However, the mechanism of PPS pulp improving para-aramid paper is still unclear. Herein, the structure change and interface behavior of composite paper during hot pressing were studied. The surface of ACFs was modified by PPS pulp in-situ melting and self-wetting at high temperatures, which made the surface of ACFs rough and viscous. ACFs were staggered in three-dimensional space, and countless network nodes were formed at the staggered parts. With the node as the vertex and the ACF as the side length, countless stable triangular structures were formed. Under this structure, the tensile fracture surface of the composite paper showed the splitting of the bulk structure of aramid fiber, indicating that the paper had strong interfacial strength. More importantly, PPS pulp breaks the limitation of weak interfacial strength between ACFs and resin matrix. We can predict that PPS pulp can be made into advanced paper-based materials with other high-performance inert fibers.