Assessment of the Co-crystallization of Ethylene/1-Octene Copolymer Blends by CRYSTAF and TREF

Published in: Macromolecular Symposia. Polyolefin Characterization, ICPC 2018.
Volume 390, 2015, Pages 01-09. Wiley-VCH
Authors:Laura Santonja-Blasco, Benjamín Monrabal
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Abstract:

The crystallization of blends of ethylene/1–octene copolymers with different comonomer content (0.3, 1.3, and 2.5 mol%) is investigated as a function of the comonomer content of the copolymers and the concentration of the copolymers in the blend (20, 50, and 80 wt%) by using techniques based on separation by crystallizability. Crystallization fractionation and the temperature rising elution fractionation (TREF) techniques provide the chemical composition distributions of the copolymers in the blend; however, fast cooling rates modify the theoretical distribution because of the cocrystallization of chains with close composition. The copolymer blends analyzed with a difference in comonomer content up to 1.2 mol%, cocrystallize upon rapid cooling rates. The extent of cocrystallization increases when reducing the concentration of the copolymer with less co-unit content in the blend. Comparing the techniques at identical cooling rates, cocrystallization is reduced by using TREF albeit coelution may appear.