Rheological behavior and nonisothermal crystallization of polypropylene/epoxidized natural rubber blends

Blends of polypropylene (PP) with epoxidized natural rubber (ENR) were prepared using melt mixing. Dynamic mechanical analysis (DMA) was employed to investigate the miscibility of the two polymers. The morphology evolution with changes of composition was studied using scanning electron microscopy (SEM). Dynamic shear tests were carried out within a frequency range of 0.01 to 100 rad/s at different temperatures. It was found that the dynamic viscosity of the blend increases significantly with increasing ENR content. The shear thickening can take place at low shear frequencies, depending on temperature and composition. Isothermal plots of log G(I) (storage modulus) against log G(II) (loss modulus) were obtained. According to the temperature dependence of the plots, the miscibility of the blends is discussed. Differential scanning calorimetry (DSC) was used to investigate the nonisothermal crystallization of the blends. The crystallization process can be described by the modified Ozawa kinetic equation. The values of the kinetic parameter, F(T), were calculated It was found that the crystallization capability of PP in the blend strongly depends on the composition.