Mechanical properties and crystalline structures of PPR modified by SEBS elastomer and rare-earth beta nucleating agent

摘要

There is of great interest in modification of polypropylene random copolymer (PPR) to improve the applicability. In this study, poly(styrene-ethylene/butylene-styrene) (SEBS) and a rare-earth beta nucleating agent (WBG-II) were utilized to modify PPR (SEBS(m)-WBG-II(n)/PPR systems). The mechanical properties and crystalline structures of modified PPR were investigated. The SEBS elastomer (10 wt%)-coupled WBG-II (0.08 wt%)-modified PPR showed significantly high Izod impact strength relative to sole SEBS elastomer or sole WBG-II-modified PPR. The yield strength, flexural strength and elongation at break were limitedly affected by the modification. The SEBS elastomer partially hindered the nucleation effect of WBG-II, causing decreased relative contents of beta-crystal of SEBS(m)-WBG-II(n)/PPR systems. The SEBS elastomer and WBG-II jointly induced crazing and shear deformation absorbed more energy under external shocks, causing the improvement of toughness. The fast cooling of molding benefited Izod impact strength of modified PPR. The combined modifications of PPR throw a new light to further improve the overall performance.