Flame-Retardant Polypropylene Composites with Magnesium Hydroxide Encapsulated by Polypropylene Grafted with Maleic Anhydride

A novel surface-treated magnesium hydroxide (MH) was prepared through the encapsulation of polypropylene grafted with maleic anhydride (PP-g-MA) for the flame retardance of polypropylene (PP). Compared with surface-treating inorganic flame retardants by using conventional modifiers, this method possesses lower cost and better effects. Due to the interaction between maleic anhydride group and hydroxyl group and the similarity for the resin encapsulating inorganic particles (PP-g-MA) and matrix resin (PP), better compatibility and dispersion of MH in PP can be obtained. Therefore, it showed that MH encapsulated by PP-g-MA significantly improved the processablity, flame retardancy, and mechanical properties of the flame retardant composites. Additionally, the effects of the modified MH on the crystallization behavior of PP were also investigated through differential scanning calorimetry (DSC). Interesting results that PP-g-MA and MH had heterogeneous nucleation effect were found. Both the crystallization temperature and the crystallinity were increased by addition of MH encapsulated by PP-g-MA.