Preparation, Flame Retardancy, and Thermal Degradation of Unsaturated Polyester Resin Modified with a Novel Phosphorus Containing Acrylate

A novel reactive phosphorus-containing acrylate (ODOPB-AC) was successfully synthesized and characterized, and the flame retardant unsaturated polyester resins (FR-UPR) with various amounts of ODOPB-AC were prepared. The thermal decomposition and flame retardant properties of samples were investigated by thermogravimetric analysis (TGA), limiting oxygen index (LOI), and microscale combustion calorimetry (MCC). As the ODOPB-AC content increased, the LOI value of FR-UPR was increased, while the value of peak heat release rate (PHRR) and total heat release (THR) were reduced. The evolved gas analysis and condensed thermo-oxidative degradation process of UPR and FR-UPR were monitored by thermogravimetric analysis/infrared spectrometry (TG-IR) and real-time infrared spectrometry (RT-IR), providing insight into the thermal degradation mechanism. ODOPB-AC acted in the gas phase through flame inhibition and in the condensed phase through charring. Moreover, scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) were used to explore the morphology and chemical components of the char.