Synthesis and mechanical properties of flame retardant vinyl ester resin for structural composites

Abstract Halogen-based fire retardants are often used to reduce flammability and improve the fire resistance properties of polymers and fiber-reinforced polymer composites (FRPs). Brominated vinyl ester resins (Br-VERs) are a class of halogenated polymer matrices that are economically viable, high performance materials that are widely utilized in composites for specialty applications, such as the fabrication of hulls in naval vessels. In this work, Br-VE polymer is synthesized from tetrabromobisphenol A (TBBPA) and glycidyl methacrylate (GMA) precursors, and which can be derived from the wastes of the biodiesel and wood pulp industries, respectively. The Br-VE reaction products are analyzed by 1 H NMR and the presence of unreacted (nonfunctional), monofunctional and difunctional TBBPA are confirmed. A baseline formulation of difunctional Br-VE and styrene (40 wt %) is mixed with a commercial brominated vinyl ester resin (Derakane 510-40A) in ratios of 20, 50 and 80 pph. Two reduced styrene content formulations of Br-VER (30 wt % styrene and 20 wt % styrene) were also prepared. The thermomechanical properties of all seven neat resin formulations were investigated using differential scanning calorimetry (DSC), rheology and dynamic mechanical analysis (DMA). The autocatalytic cure kinetics parameters and chemorheological behavior enable development of a cure cycle for the thermosetting resin. The DMA results demonstrate that all resin formulations comprising Br-VER exhibit improved mechanical performance as compared to the commercial vinyl ester resin.