Study On The Preparation Process And The Performance Of TiO₂/PP Composites Prepared With Continuous Mixing Extruder

In purpose of improving the performance of TiO₂ filled polypropylene （PP） composites, the paper focuses on the composite preparation procedures, especially in consideration of the mixing characteristic of continuous mixing extruder. Flow field characteristics in the mixing section of continuous mixing extruder were studied using Polyflow software. TiO₂/PP composite was prepared through a lot of blending experiments with different process conditions and rotor structure. In order to characterize the microstructure and macro physical and mechanical properties of the composite material, DSC, SEM, multifunctional mechanical testing machine, cone plate rheometer and other instruments and equipment were used; the resistance to escherichia coli and staphylococcus was experimentally characterized by bacterial culture experiments. The effect of mixing rotor structure, mixing flow field characteristics, rotor speed, TiO₂ content etc. on the physical and mechanical properties and antibacterial properties of composite materials were discussed. The mainly results are as follows:（1） The TiO₂ was beneficial to the improvement of the crystallinity of PP. TiO₂ has the role of heterogeneous nucleation in PP that makes crystal granularity smaller. The more smaller TiO₂ reunion in the PP matrix size, the more faster crystallization rate of composites and higher the degree of crystallinity.（2） The simulation results showed the increase of rotor speed enhanced the dispersion and distribution of TiO₂ in PP matrix. Experiments showed that the overall mechanical performance of TiO₂/PP composite prepared with the new form mixing rotor was optimum while rotor speed was 800 rpm and TiO₂ content was 3%.（3） Experiment results also showed that the antibacterial properties of composite materials was optimum while TiO₂ content was 3% and the rotor speed was 800 rpm.; At the same time, for different species, different light source and different aging antibacterial the sterilization efficiency of TiO₂/PP composite can reach more than 99%.