Liquid-liquid phase separation in blends containing copolymers produced using metallocene catalysts

Three commercial copolymers, two ethylene-butene and one ethylene-hexene, produced using metallocene catalysts, were each blended with a commercial linear polyethylene to form binary blends of various compositions. The three copolymers had quite similar molecular weights and molecular weight distributions. The blends were examined, using indirect experimental methods, to see if there was any phase separation in the melt. All three systems show phase separation in the melt at low linear polyethylene content at temperatures between about 125 degrees C and 170 degrees C. The behaviour of the linear/ethylene-hexene copolymer system was very similar to the behaviour of the two linear/ethylene-butene copolymer systems. Further, the behaviour of these blends is very similar to that which has been found for binary linear/lightly branched polyethylene blend systems where the copolymers were polymerized by other processes. (C) 1997 Elsevier Science Ltd.