BLENDS OF HOMOGENEOUS ETHYLENE-OCTENE COPOLYMERS

Blends of ethylene-octene copolymers prepared by Dow's INSITE(TM) cons trained geometry catalyst and process technology were characterized. ( INSITE(TM) is a trademark of The Dow Chemical Company.) A previously d escribed classification scheme based on density, or comonomer content, was the basis for the choice of blend components. The blends combined a low density Type I copolymer (0.865 g cm(-2)) with a higher density copolymer. The second component was either another Type I copolymer ( 0.887 g cm(-3)), a Type II copolymer (0.901 g cm(-3)), or a Type III c opolymer (0.913 g cm(-3)). The melting and crystallization behaviour s uggested that the components crystallized separately in all the blends . However, dynamic mechanical analysis indicated that the noncrystalli ne portions of the Type I blends formed a single phase, whereas the no ncrystalline regions of blends with the Type II or Type III copolymer appeared to be phase separated in the solid state. The stress-strain b ehaviour at ambient temperature correlated with density, or total crys tallinity, regardless of whether the material was a copolymer or a ble nd. (C) 1997 Elsevier Science Ltd.