Influence of crystallization on intercalation, morphology, and mechanical properties of polypropylene/clay nanocomposites

Intercalated nanocomposites of polypropylene (PP)/clay (PPCNs) were prepared by a melt extrusion process using maleic anhydride modified PP (PP-MA) and organophilic clay. The extent of intercalation of PP-MA chains in the space between silicate galleries increased with crystallization temperature T-c and decreased as clay content increased. As compared to matrix PP-MA, the dispersed clay particles in the PP-MA, matrix acted as a nucleating agent and lowered the spherulite dimension with increasing clay content as revealed by light scattering experiments and polarizing optical microscopy. The PPCN crystallized at high T-c showed that a certain extent of segregation of the dispersed clay particles takes place around the boundary of the spherulites (interspherulite). Extensive intercalation occurred during crystallization, especially at high T-c due to the long time for full solidification of the melt. The degree of intercalation of PP-MA chains in the silicate galleries strongly depends on the time in the molten state. The effect of the intercalation through organophilic interaction on the dynamic storage modulus of the PPCNs crystallized in the temperature range of 70-130 degreesC has been emphasized.