Effect of cocrystallization on kinetic parameters of high-density polyethylene/linear low-density polyethylene blend

The isothermal crystallization kinetics of a binary melt blend of high-density polyethylene (HDPE)/linear low-density polyethylene (LLDPE) is presented. An effort was made to understand the phenomenon of cocrystallization between these two constituting components of the blend with the help of kinetic parameters. The analysis based on the Avrami exponent entails that both HDPE and LLDPE undergo individual seeding of nuclei and they merge with each other in the growth process to form cocrystallites. The incorporation of the LLDPE segment in the HDPE crystallites progressively dilutes the properties of HDPE in the blend. The half-time of crystallization (t_1/2) shows variation in three distinct stages: The t_1/2 increases slowly in the region of 0–30% LLDPE content (HDPE-rich blend), remains constant in the 30–70% LLDPE-containing region (middle region of blend composition), and increases sharply thereafter. These variations of t_1/2 quite appreciably explain the change in % crystallinity, the Avrami exponent, and crystallite-size distribution. These observations were further supported by the small-angle light-scattering experiment. © 1996 John Wiley & Sons, Inc.