Effect of Different Shear Modes on Morphology and Mechanical Properties of Polypropylene Pipes Produced by Rotational Shear

摘要

Oriented “shish-kebab” structures could be obtained by shearing to enhance the mechanical properties of polymer samples markedly.However,the effect of shear mode on mechanical properties is still uncertain.The study of stepped hoop shear field on the isotactic polypropylene(iPP)pipe was developed through applying a self-designed rotational shear system(RSS).The effect of stepped shear field on the microstructure and comprehensive properties of iPP pipe was investigated by the comparison with continuous shear.It could be found that the loosely-assembled shish-kebabs with the larger size were formed in the continuous shear pipes,but the smaller and tightly-stacked ones existed in the pipes with stepped shear.Surprisingly,due to differential morphologies under different shear modes,better comprehensive mechanical properties were obtained in the pipes with stepped shear.