Synthesis of a novel vinyl ester resin and its glass fiber composite with good flame retardant and mechanical properties

Vinyl ester resin (VER) and its glass fiber composites are widely utilized in various industries due to the excellent overall properties. However, flame retardancy remains a key factor limiting the broader application of VER. In this study, we synthesized a new intrinsically flame-retardant vinyl ester resin monomer OPBMA-DOPO, through the reaction of Schiff base and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO), and compared its properties with the commercial VER resin. The cured sample (OPBMAR-DOPO) and its glass fiber composite (OPBMAR-DOPO/GF) exhibit excellent flame retardant properties. Compared to VER, OPBMAR-DOPO exhibits a 51.18 % reduction in total heat release (THR) and a 40.55 % decrease in total smoke production (TSP). When compared to VER/GF, OPBMAR-DOPO/GF shows a 9.76 % decrease in THR and a 28.7 % reduction in TSP. The limited oxygen index (LOI) of OPBMAR-DOPO is 29.2 %, and for OPBMAR-DOPO/GF is 48.2 %, which are significantly higher than that of VER and VER/GF. Additionally, the mechanical properties of OPBMAR-DOPO and its glass fiber composite are superior to VER. Furthermore, the flame retardant mechanism of OPBMAR-DOPO was investigated. This study contributes to expanding the application areas of vinyl ester resin.