Flame Retardancy\nand Thermal Properties of Novel UV-Curable Epoxy Acrylate Coatings\nModified by a Silicon-Bearing Hyperbranched Polyphosphonate Acrylate

Abstract

A novel\nsilicon-containing hyperbranched polyphosphonate acrylate (HPA), successfully\nsynthesized via the Michael addition polymerization of tri­(acryloyloxyethyl)\nphosphate (TAEP) with (3-aminopropyl)­trimethoxysilane (KH550), was\nincorporated into the epoxy acrylate resin (EA) to prepare UV-curing\nflame retardant coatings. The study of thermal degradation of these\ncoatings revealed that HPA can catalyze the degradation of EA, contributing\nto the formation of thermally stable char layer. The residues of EA/HPA-3\n(which contains 30 wt % HPA) at various temperatures were analyzed\nby X-ray photoelectron spectroscopy (XPS) and the results displayed\nthat phosphorus and silicon elements can well protect the carbonaceous\nchar from thermal-oxidative degradation at 600 °C, but do not\nwork at 800 °C. Besides, the investigation of the flammability\nillustrated that the addition of HPA increased the limiting oxygen\nindex (LOI) value and reduced the peak heat rate release (HRR) and\ntotal heat release (THR).