Non-isothermal crystallization behavior of PP/Mg(OH) 2 composites modified by different compatibilizers

Abstract

Polypropylene (PP) blends with three kinds of grafted macromolecules, PP/Mg(OH) 2 composites and its composites modified by different compatibilizers were prepared by melt extrusion in a twin screw extruder. The crystallization and melting behaviors of PP blends and PP/Mg(OH) 2 composites were investigated with differential scanning calorimeter (DSC). The results indicated that addition of PP-g-MA has no influence on the crystallization temperature of PP, but POE-g-MA and EVA-g-MA decrease the crystallization temperature of PP. For PP/Mg(OH) 2 composites, addition of Mg(OH) 2 increases the crystallization temperature of PP and induces the formation of β-crystal in PP matrix. For PP/Mg(OH) 2 composites modified by different compatibilizers, the synergism effect of heterogeneous nucleation of Mg(OH) 2 and PP-g-MA or POE-g-MA further increases the crystallization temperatures. For PP/Mg(OH) 2 composites modified by EVA-g-MA, the addition of EVA-g-MA to PP/Mg(OH) 2 composite has little effect on the crystallization and melting behavior of PP. It is suggested the synergism effect of heterogeneous nucleation of Mg(OH) 2 and compatibilizer depends upon the compatibilization between PP and compatibilizer. The increase in crystallization temperatures of PP in PP/Mg(OH) 2/compatibilizer facilitates the formation of α-PP, but weakens the formation of β-PP.