Improved processability and optimized preparing process for fire-safe poly (ethylene terephthalate) by electron effect modified Schiff base

To get better processability and preparing process of Poly (ethylene terephthalate) polymer, -NO 2 was used to modify Schiff Base to synthesize a novel flame retardant monomer of 5-([3-nitrobenzylidene] amino) isophthalic acid (BNA) to prepare flame retardant and anti-dripping PET copolyester (BNA n PETs), where the electron effect of -NO 2 passivate the cross-linking reactivity of BNA in BNA n PETs to enhance its cross-linking temperature to improve its processing zone with better processability. The results demonstrated that the cross-linking temperature of BNA n PETs was improved from the range of (250–348°C) to (355–385°C), and BNA accelerated the reaction of the polycondensation of PET for saving time of 42%. -NO 2 enhanced the residue char of BNA n PETs in high temperature and further improved its flame retardancy. BNA 10 PET with 7.2 mol% of BNA had LOI of 31.8% and V-0 of UL-94 without drip, and the introduction of –NO 2 did not change the flame retardant mechanism in BNA n PETs.