Isothermal crystallization kinetics of polypropylene/attapulgite nanocomposites

Attapulgite (ATP) was first modified by a silane coupling agent and then graft-polymerized with butyl acrylate (BA). The polypropylene (PP)/modified-ATP nanocomposite was synthesized via melt blending in a mixer apparatus. Crystallization behavior and morphology of the PP/ATP nanocomposites were studied by differential scanning calorimetry (DSC) and polarizing optical microscopy (POM). In particular, the isothermal crystallization kinetics of the PP/ATP nanocomposite were investigated in detail. From the melting and cooling curve plots, it was found that the degree of crystallinity slightly increased, and the equilibrium melting temperature also was slightly enhanced with the increase of ATP content. The isothermal crystallization kinetics showed that the addition of modified ATP increased both the crystallization rate of PP and the isothermal Avrami exponent. The POM photographs indicated that the spherulites of the PP/ATP nanocomposites were greatly decreased in size as ATP content increased, suggesting that the dispersed ATP particles in the PP matrix acted as nucleating agents.