Presented at the 7th International Conference on Polyolefin Characterization (ICPC), 2018. Houston, TX, USA.
By Laura Santonja, Benjamín Monrabal. Polymer Char, Spain.
The chemical composition distribution of copolymers plays an important role during the crystallization process of blends of random ethylene 1-alkene copolymers, because crystallizable sequences of both materials may crystallize in the same range of temperatures. Cocrystallization is the phenomenon arising, in miscible blends of similar chain conformation components, when the crystallizable chains of both copolymers conform in a single crystal phase (isomorphous polymers) as occurring for the polyethylene and its copolymers.
Some studies about the crystallization of ethylene/1-olefins copolymer blends using these analytical techniques in dilute solution and solid-state have been reported. The extent of cocrystallization in both CRYSTAF and TREF is higher when the chain crystallizabilities between components are close and the crystallization rate increases. However, in these works the effect of copolymer concentration in the blend was not extensively reported. This study attempts to extend the studies about the cocrystallization of ethylene 1-octene blends in solution by using CRYSTAF. An analogous study is being performed by using TREF (crystallization-elution based technique) and, at the same crystallization rate, TREF provides better resolution results than CRYSTAF. However, only CRYSTAF can evaluate the real cocrystallization extent of the blends.