Grafting alkynyl groups on the surface of nano‐aramid fibers towards flame retardant thermoplastic polyurethane

Abstract

AbstractIn this work, para‐aramid fibers were dispersed into para‐aramid nanofibers (ANF) by deprotonation process, and then modified by 3‐chloropropyne (PC) via covalent bonding interaction. The resultant nanofiber (ANF‐PC) as a flame retardant was blended with thermoplastic polyurethane (TPU) to obtain fire‐retardant TPU nanocomposites. The addition of 0.250 wt% ANF‐PC reduced the peak heat release rate, total heat release, total smoke release, and peak CO release rate of TPU by 47.7%, 31.5%, 16.4%, and 45.1%, respectively. The char yield of TPU/ANF‐PC0.250 was increased from 7.7% (TPU/ANF0.250) to 13.7%. The flame‐retardant effect of ANF‐PC in TPU composites can be attributed to its carbonization effect in the condensed phase, which increased the char yields and graphitization degree of char residue. In addition, the presence of ANF‐PC increased the tensile strength and breaking strain of TPU by 645% and 578% compared to untreated ANF, due to the improved dispersion state of ANF‐PC.