HETEROGENEOUS NUCLEATION OF Mg(OH)_2/POLYPROPYLENE COMPOSITES MODIFIED BY FUNCTIONALIZED POLYPROPYLENE

The heterogeneous nucleation of Mg(OH)_2/polypropylene composites modified by addition of functionalized polypropylene (FPP) or grafting monomer and the formation of in-situ FPP were investigated by DSC. The results indicated that the heterogeneous nucleation induced by Mg(OH)_2 surface increases the crystallization temperatures of PP. Addition of FPP into Mg(OH)_2/PP composites further increases the crystallization temperatures of PP, attributed to the activation of the heterogeneous nucleation of Mg(OH)_2 by addition of FPP. The addition of grafting monomer also further increases the crystallization temperatures of PP in Mg(OH)_2/PP composites, but crystallization temperatures of PP is no influenced by the monomer content. It is explained by the heterogeneous nucleation of the Mg(OH)_2 surface activated by in-situ FPP. The formation of in-situ FPP results in a reduced crystallization temperature, melting point and degree of crystallization due to the decreases regularity of PP chain. It is suggested that there exist a synergistic effect of the heterogeneous nucleation of Mg(OH)_2 surface and activation of FPP and monomer to the heterogeneous nucleation of Mg(OH)_2 surface to increase the crystallization temperature of PP. However, The crystallization and melting temperatures of Mg(OH)_2/PP composites modified by in-situ FPP are lower than that of Mg(OH)_2/PP composites modified by addition of FPP or monomer.