When the nanosize particles of titanium dioxide (TiO 2 ) are well dispersed into the polypropylene (PP) matrix, the inorganic nanocomposites, PP/TiO 2 , has more significant material properties than the net PP polymer. Based on the finite element method, the sol-gel reaction process of preparation PP/TiO 2 nanocomposites in an internal batch mixer with Haake rotors was simulated with user defined functions (UDFs) of Polyflow software. In order to better understand the effect of chaotic flow strength induced by asymmetric flow field on the reaction rate, the Poincaré maps, the line stretch and stretching mixing efficiency in the batch mixer were calculated under different speed ratios. Moreover, the effects of rotor speed ratio, temperature rise by viscous heating, and precursor concentration on the overall conversion rates in the mixer were discussed, respectively. Especially, the effect of chaotic strength by different speed ratios on the part and overall reaction rate within the mixer were carried out. It is found that the chaotic mixing intensity and average conversion rate increase gradually with the increase of the speed ratios in the mixer. Interestingly, the greater the intensity of the chaotic flow field in the internal mixer, the more sensitive of the average conversion rate to the temperature rise.

The internal mixer is an important devise for processing the polymer nanocomposites acting as a chemical reactor. In this article, based on the computational fluid dynamics method, the fluid transportation and heat transfer analysis of solgel reaction processing for Polypropylene (PP)/TiO 2 nanocomposites in the internal batch mixers with single-winged and two-winged Cam rotors were simulated. First, the Lagrangian coherent structure analysis was used to understand the fluid transport properties in the mixers. Then the effect of rotational speeds (ratios) and barrel temperatures on the heat transfer characteristics in the mixers with different rotors was analyzed. Also, the changes of viscous heating and torques of rotors with different thermal conditions in the mixers were discussed. Especially, the relationship between the fluid transportation and heat transfer characteristics was explored. The results show that a big rotor speed ratio can induce great fluid transportation in the left and right mixer chambers based on the Lagrangian coherent structure analysis, and the fluid near the horseshoe map has great folding effect and temperature magnitude. The viscous dissipation, viscous heat generation, and rotor torques in the mixers increase with increasing the rotational speeds and decrease with increasing the barrel temperatures. The mixer with two-winged rotors has higher average temperature, viscous dissipation, viscous heat generation and the torques of rotors values of reactive fluid than that with single-winged rotors.