Influences of SiO2 coated modified nano-TiO2 particles on extensional rheological property and crystallization behavior of polypropylene

In order to investigate the spinnability and processing performance of the photocatalytic functional polypropylene (PP) fiber, SiO2 coated modified nano-TiO2 particles (SiO2@TiO2) were used as additive and PP was modified by blending firstly. Then, the extensional rheological properties of SiO2@TiO2/PP blend melts were tested by capillary rheometer, and the influences of SiO2@TiO2 on the properties of PP were studied by XRD and DSC. The results demonstrate that the SiO2@TiO2/PP blend melts belong to the fluids of extensional thinning type. With the increasing of temperature, both of the extensional stress and extensional viscosity of melts decrease; extensional viscosity increases with the increasing of additive amount, and extensional flow activation energy reduces with the increasing of extensional strain rate. The addition of SiO2@TiO2 does not change the crystalline structure of PP significantly, but enhance the performance of crystallization. When the content of SiO2@TiO2 is 4wt%, the crystallinity of the blend melt is 8.6% higher than that of pure PP. SiO2@TiO2 leads PP to form more compact crystal structure, which has important influences on the properties of materials. ©, 2015, Beijing University of Aeronautics and Astronautics (BUAA). All right reserved.