A facile strategy for fabricating aramid fiber with simultaneously high compressive strength and high interfacial shear strength through cross-linking promoted by oxygen

Low axial compressive strength derived from weak lateral interaction of aramid fiber is one of the major obstacles for its engineering application. Introducing cross-linking is an effective method to improve the property. In this study, Poly-(benzimidazole-terephthalamide) (PABI) fiber was synthesized and prepared by wet-spinning, followed by heat-treating at different conditions for formation of cross-linking. During the process, trace amount of oxygen was introduced and it was confirmed that oxygen had great influence on the cross-linking reaction. The finding was characterized in detail. It is found that cross-linking of PABI can take place upon 330 °C and cross-linking site is located in phenyl on benzimidazole moieties because of its higher electron density. Trace amount of oxygen can significantly catalyze the cross-linking reaction and make cross-linking degree improve. Compressive strength increases by over 50% and interfacial shear strength is improved by nearly 28% after cross-linking on the basis of maintaining excellent mechanical properties.