Hybrid blends of similar ethylene 1-octene copolymers

D. Rana et al., Hybrid blends of similar ethylene 1-octene copolymers, POLYMER, 41(19), 2000, pp. 7067-7082
Citations number
Categorie Soggetti
Organic Chemistry/Polymer Science
Journal title
ISSN journal
0032-3861 → ACNP
Year of publication
7067 - 7082
SICI code
Two binary blends of FA + FM and SF + FM comprising ethylene 1-octene copol ymers (EOC), one component prepared by Ziegler-Natta and another by metallo cene catalysts were investigated in terms of the thermal, viscoelastic, rhe ological, mechanical, and morphological properties. The big difference betw een the Ziegler-Natta and metallocene catalyzed EOCs is the distribution an d the length of the side chain branching. Each component in FA + FM has sim ilar melt index (MI), density, and comonomer content, while that of the sec ond pair (SF + FM) has similar MI and density, but differs in comonomer con tent. Both the melt and solution blended materials exhibit two distinct mel ting and crystallization peaks, implying that the constituents exclude one another during crystallization. A single beta relaxation shifted to lower t emperature with the content of metallocene EOC, indicates miscibility in th e amorphous region, while the gamma transition is observed in the same posi tion within experimental error. Rheological observations suggest the FA + F M to be miscible, but not SF + FM, implying that the difference in the dist ribution and the length of the side chain branching influences the melt pro perties of the EOC blends regardless of the similarity in the density and M I. In addition, no dependency of comonomer contents and the difference in t he side chain branching on the mechanical properties is observed. Morpholog ical studies observed from the slow cooled specimens show large spherulitic diameter and ring space for the Ziegler-Natta EOC. In particular, grass li ke spherulitic sheaf structure is dominated in the blend by the addition of metallocene EOCs. Hence the properties of the hybrid blends consisting of similar MI and density are influenced by not only the distribution of the c omonomer, but also the length of the side chain branching. (C) 2000 Publish ed by Elsevier Science Ltd. All rights reserved.