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

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 polymeric flame-resistance field. [ABSTRACT FROM AUTHOR]