Non-isothermal crystallization kinetics of polypropylene/organic-rectorite nanocomposites

The polypropylene (PP)/organic rectorite (OREC) nanocomposites were prepared by extruding the mixtures of OREC and PP using a twin-screw extruder. The crystallization behavior of PP and PP/OREC nanocomposites was studied by wide angle X-ray diffraction analysis (WAXD) performed at angle range of 10-25° and differential scanning calorimetry (DSC) conducted at constant cooling rate of 2.5 K/min, 5 K/min, 10 K/min and 15 K/min, respectively. The results of WAXD analysis show that the introduction of OREC does not change the crystal form of PP in the compocites. Non-isothermal crystallization kinetics of PP and PP/OREC nanocomposites was investigated by means of DSC, and the data are successfully analyzed by the Jeziorny and the Mo Zhishen methods. The non-isothermal crystallization kinetics parameter (Z_c) and Avrami exponent (n) for PP and PP/OREC nanocomposites were reduced with cooling rate increasing. However, for PP/OREC nanocomposites, they are higher than those of PP at the same cooling rate. The characteristic cooling rate, F (T), increases with the degree of crystallinity for both PP and PP/OREC nanocomposites, but the values of F(T) of PP/OREC nanocomposites were lower than those of PP at the same degree of crystallinity. All the above analyse indicate that particles of OREC have heterogeneous nucleation effects on PP matrix.