Shear rheological properties of SiO_2-coated TiO_2 particles and polypropylene blend

Polypropylene( PP) was modified by blending with the modifier of Si O2-coated Ti O2 nanoparticles,and a twin-bore capillary rheometer was used to analyze the shear rheological properties of the blends. The results show that the non-Newtonian behavior of PP is enhanced by adding the modifier.When the shear rate is at 500 s- 1,the non-Newtonian index of the blends with mass fraction of 6% was27. 1% lower than pure PP; and it was 14. 3% lower than that pure PP when the shear rate is at 4 500 s- 1.Furthermore,the adding of the modifier can improve the flow resistance of PP. Compared with pure PP,the viscous flow activation energy and shear viscosity of the blends with the modifier mass fraction of 6%were increased by 68. 4% and 22. 1%,respectively,under the shear rate of 1 184. 29 s- 1at 240 ℃.Raising the temperature can significantly improve the melt flow properties. At shear rate of 584. 80 s- 1,the shear viscosity of the blends with adding amount of 6% was decreased by 37. 1% at 250 ℃ compared with that at 230 ℃. Experimental results indicated that the spinnability of the blends can be improved by the proper control of adding proportion,melting temperature and extrusion process.