A comprehensive enhancement of the optical, mechanical, low dielectric, and flame-retardant characteristics of epoxy resin by the incorporation of multifunctional additive

Abstract

Epoxy resin is widely utilized but faces the drawback of flammability. However, adding flame retardants often results in the compromise of other properties, such as mechanical and optical characteristics. In this study, a phosphorus-nitrogen multifunctional flame retardant named DPVPI was successfully synthesized. The resulting epoxy resin containing DPVPI demonstrated good transparency and low dielectric constant. Furthermore, the unique structure of DPVPI led to additional enhancements in the mechanical properties of EP composite. The tensile strength of EP composite was increased by 33 %, and the impact strength was improved from 13.61 kJ/m² to 25.74 kJ/m². Remarkably, the composites with Only 4wt% DPVPI can achieve a V-0 rating in the UL-94 test and the maximum limiting oxygen index (LOI) of it reached 32.6 %. The cone calorimeter test showed that the peak heat release of the composites with a 5 wt% addition decreased by 35 %, the total smoke release decreased by 37 %, and the char yield doubled. This research presents a novel strategy for subsequent synthesis endeavors about multifunctional flame retardants.