Toughening of PP/EPDM blend by compatibilization

To improve the mechanical properties of blends of polypropylene (PP) and te rpolymer of ethylene-propylene-diene, (EPDM), a triblock copolymer, (PP-g-M AH)-co-[PA-6,6]-co-(EPDM-g-MAH), was synthesized by coupling reaction of ma leic anhydride (MAH)-grafted PP (PP-g-MAH), EPDM-g-MAH, and PA-6,6. The new ly prepared block copolymer brought about a physical interlocking between t he blend components, and imparted a compatibilizing effect to the blends. I ntroducing the block copolymer to the blends up to 5 wt % lead to formation of a beta-form crystal. The wide-angle X-ray diffractograms measured in th e region of 2 theta between 10 degrees and 50 degrees ascertained that inco rporating the block copolymer gave a new peak at 2 theta = 15.8 degrees. Th e new peak was assigned to the (300) plane spacings of the beta-hexagonal c rystal structure. In addition, the block copolymer notably improved the low -temperature impact property of the PP/EPDM blends. The optimum usage level of the compatibilizer proved to be 0.5 wt %. (C) 2000 John Wiley & Sons, I nc.