PARTICLE COARSENING IN POLYPROPYLENE POLYETHYLENE BLENDS/

We report the results of particle growth in a polydisperse blend syste m as a function of(i) heat treatment temperature (190, 220, 250, and 2 80 degrees C) and (ii) time of heat treatment (0-290 min) for three bl ends of isotactic polypropylene and linear low-density polyethylene, p repared by melt extrusion. To a first approximation, the growth of the particles obeys the t(1/3) law; however, the polydispersity of the so lute polymer has an effect on this relationship. The dependence on mol ecular weight is analyzed, and it is shown that for polydisperse solut e the gradient of growth should decrease with time.