IPP HDPE BLENDS .2. MODIFICATION WITH EPDM AND EVA/

Past work has shown that addition of high-density polyethylene (HDPE) to polypropylene (PP) resulted in a significant reduction in the elong ation at break and in the gate-region impact strength of injection mol ded articles. In this study, we report on the compatibilization of the se blends with ethylene/propylene/diene monomer (EPDM) or ethylene/vin yl acetate (EVA) copolymers. EPDM is effective at improving the impact strength ard gate puncture resistance of a 90/10 PP/HDPE blend. EVA, on the other hand, is effective at improving the impact strength and t he elongation at break of this material. It was also found that EVA is a better impact modifier for PP than is EPDM. DSC analysis indicated that EPDM, when blended with PP, caused a significant reduction in the degree of crystallinity of the PP. This was not observed in the case of EVA/PP blends. Further, our results indicate that care must be take n in designating a particular material as a better compatibilizer than some other material. It is crucial that conditions be attached to the label compatibilizer, indicating in particular the desired mechanical properties of the blend. (C) 1996 John Wiley & Sons, Inc.