Nonisothermal melting and crystallization studies of homogeneous ethylene/α‐olefin random copolymers

Abstract

A study of nonequilibrium melting, nonisothermal, and isothermal crystallization behavior of ethylene/1-octene (EO) random copolymers, produced using metallocene catalysts has carried out. As branch (or defect) content increases, the nonisothermal and isothermal crystallization rates, melting temperatures, and heats of fusion decrease. There is also a branch length effect on melting temperature depression, the melting temperature depression of EO random copolymers with hexyl branches were significantly larger than those of ethylene/1-butene (EB) and ethylene/1-propene (EP) copolymers having ethyl and methyl branches, respectively. The melting temperatures of homogeneous random copolymers have been found to be always lower than those of fractions of heterogeneous copolymers, having approximately the same branch content and molecular weight. Hence, defect distribution in copolymer systems is at least as important a parameter as the defect content. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 70: 1893–1905, 1998