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Crosslinking of ethylene–octene copolymers under dynamic conditions: A new way to access polymeric hyperbranched structure
Author(s) -
Msakni A.,
Chaumont P.,
Cassagnau P.
Publication year - 2006
Publication title -
polymer engineering and science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.503
H-Index - 111
eISSN - 1548-2634
pISSN - 0032-3888
DOI - 10.1002/pen.20618
Subject(s) - materials science , copolymer , shearing (physics) , octene , ethylene , polymer chemistry , branching (polymer chemistry) , chemical engineering , composite material , polymer , organic chemistry , chemistry , catalysis , engineering
The crosslinking process of ethylene–octene copolymers by dicumyl peroxide (DCP) has been studied under static and dynamic conditions. Under static conditions, our results (gel time, insoluble fraction, and equilibrium modulus) qualitatively agree with the theories on the prediction of properties of random crosslink network. Furthermore, it can be concluded that the chain linking reaction is dominant and that the beta chain scission can be neglected for these copolymers. We report an original and new result: under dynamic conditions, inside the chamber of a batch mixer, the dynamically crosslinked samples are reprocessable, meaning that the final microstructure is totally different from that obtained under static conditions. Indeed, the samples crosslinked under shearing and mixing are soluble and the size exclusion chromatography analysis revealed a broad molecular weight distribution with a significant tail of high molecular weights situated around 10 6 g/mol. This molten media can be imagined as a continuum of clusters of different multiscale sizes from the size of a free precursor chain to larger clusters of high molecular weights. Actually, the balance between reaction and mixing efficiency is the controlling parameter for the development of this hyperbranched structure under dynamic conditions. POLYM. ENG. SCI., 46:1530–1540, 2006. © 2006 Society of Plastics Engineers