Preparation of a Chitosan-Based Flame-Retardant Synergist and Its Application in Flame-Retardant Polypropylene

摘要

A novel flame-retardant synergist, chitosan/urea compound based phosphonic acid melamine salt (HUMCS), was synthesized and characterized by Fourier transform infrared spectroscopy and ~(31) P-NMR. Subsequently, HUMCS was added to a fireretardant polypropylene (PP) compound containing an intumescent flame-retardant (IFR) system to improve its flame-retardant properties. The PP/IFR/HUMCS composites were characterized by limiting oxygen index (LOI) tests, vertical burning tests (UL-94 tests), microscale combustion calorimetry tests, and thermogravimetric analysis to study the combustion behavior and thermal stability. The addition of 3 wt % HUMCS increased the LOI from 31.4 to 33.0. The addition of HUMCS at a low additive amount reduced the peak heat-release rate, total heat release, and heat-release capacity obviously. Furthermore, scanning electron micrographs of char residues revealed that HUMCS could prevent the IFR-PP composites from forming a dense and compact multicell char, which could effectively protect the substrate material from combusting.