Peroxide modified polyolefin blends—Part II: Effects on LDPE/PP blends with polymer components of dissimilar initial viscosities

Blends of high viscosity polypropylene (PP) and low viscosity low density polyethylene (LDPE) were prepared in the Brabender batch intensive mixer. The rheological mismatch of these immiscible blend components resulted in coarse blend morphologies and poor mechanical properties. By reacting these blends with 1800 ppm Lupersol 101 peroxide at 180°C, the morphology became much finer and, at 50/50 weight ratio, assumed co‐continuous phase structure. As a result, the mechanical properties improved significantly. The above observations are attributable to the fact that the peroxide reaction at this level of concentration removes the rheological disparity of the blend components, a condition that is more favorable for efficient dispersive mixing. It has been frequently stated that the scale and uniformity of dispersive mixing affects the uniformity and controllability of reactions occuring in molten blends. This work shows, for the first time, that reactions with peroxides alter the blend morphology in a beneficial manner. The two phenomena are, therefore, mutually dependent.