Improved Flame Retardancy and Thermal Stability of P-and N-containing Diphenol Epoxy Resins from Lignin Oxidation Degraded Derivatives

Abstract

Diphenols with structures similar to bisphenol A (BPA) were designed and synthesized from three kinds of lignin oxidative depolymerized derivatives (LODD) to investigate the substitution possibility of BPA by LODD as raw material. The chemical shift and integral area of nuclear magnetic resonance spectra and the X-ray photoelectron spectroscopy analysis results showed that phosphorus-and nitrogen-containing diphenols were successfully formed. The cone calorimeter test and thermogravimetric analysis exhibited that the epoxy resin from diphenols were typical intumescent flame retardancy systems. These results showed drastically improved flame retardancy compared with traditional epoxy resin. Among them, the epoxy resin derived from vanillin presented the best flame retardancy properties. Due to a phosphorus-rich carbon layer being formed and accumulated at the surface of the epoxy resins from diphenols, the thermal degradation showed great enhancement of the char residues.