Influence of TiO2 on the isothermal crystallization of polypropylene containing nanocomposites

This study investigated the influence of different contents (1, 2 and 5 wt%) of TiO2 in the polypropylene (PP) using a twin screw co-rotating extruder. The influence of this inorganic nanoparticle in the isothermal crystallization kinetic monitored by differential scanning calorimetry analysis was explored. To investigate the dispersion and the microstructure of the nanocomposites was used transmission electron microscopy (TEM), X-ray diffraction (XRD) and polarized optical microscopy (POM). The results indicated that the addition of the TiO2 increased the degree of crystallinity of PP and its crystallization temperature. Besides, the nucleation and crystal growth processes were also affected mainly for the 5 wt% of TiO2 and this change can be correlated with the form of dispersion pointed out by the TEM. The parameters of the Avrami equation and the activation energy (Ea) of crystallization suggests that the finer dispersion of the TiO2 cause a restriction of the nucleation during the crystal formation and it is supported by XRD and POM analysis, which indicated the formation of lower crystals size.