Green Preparation of Expandable Graphite and Its Application in Flame-Resistance Polymer Elastomer

Abstract

Although research on expandable graphite (EG) has achieved great progress, its practical application is restricted due to high sulfur content and serious pollution during production. Herein, low-sulfur EG was prepared through a two-step intercalation method using environmentally friendly hydrogen peroxide as an oxidant. By optimizing reaction parameters and process, the as-prepared EG exhibits low sulfur content (1.85 wt %) and high exfoliation volume (282 mL g–1). Moreover, when 30 wt % EG is mixed with ethylene-vinyl acetate copolymer (EVM) matrix, the obtained EG/EVM composite exhibits a high limited oxygen index (LOI) of 30.4%, showing its excellent flame retardancy. Furthermore, for the compatibility between EG and EVM to be improved, poly(vinyl acetate) (PVAc) was grafted to EG by in situ radical polymerization. The EG-g-PVAc/EVM composite shows high flame resistant performance with improved control of fly ash. Therefore, this easily prepared EG can be broadly applied in environmentally friendly pol...