Enhanced thermal properties and flame retardancy of unsaturated polyester-based hybrid materials containing phosphorus and silicon

A phosphorus and silicon containing liquid monomer (9,10-dihydro-9-oxa-10-phosphaphenanthrene 10-oxide–vinyltrimethoxysilane (DOPO–VTS)) was synthesized by the reaction between DOPO and VTS. DOPO–VTS and methacryloxypropyltrimethoxylsilane were introduced into unsaturated polyester resin to prepare flame retardant UPR/SiO2 (FR-UPR/SiO2) hybrid materials by sol–gel method and curing process. DOPO–VTS contributes excellent flame retardancy to UPR matrix, which was confirmed by the limiting oxygen index and microscale combustion calorimeter results. The thermogravimetric analysis (TGA) results indicate that the FR-UPR/SiO2 hybrid materials possess higher thermal stability and residual char yields than those of pure UPR at high temperature region. The thermal degradation of materials was investigated by TGA/infrared spectrometry (TG-IR) and real-time infrared spectrometry (RT-IR), providing insight into the thermal degradation mechanism. Moreover, scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) were used to explore the morphologies and chemical components of the residual char. Copyright © 2013 John Wiley & Sons, Ltd.