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Polysiloxanes: paradigm or paradox
Author(s) -
Magill Joseph H.
Publication year - 1998
Publication title -
macromolecular rapid communications
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.348
H-Index - 154
eISSN - 1521-3927
pISSN - 1022-1336
DOI - 10.1002/(sici)1521-3927(19980101)19:1<65::aid-marc65>3.0.co;2-y
Subject(s) - lamellar structure , reptation , brittleness , crystallization , crystallinity , polymer science , materials science , polymer , molar mass , polyethylene , branching (polymer chemistry) , polymer chemistry , chemical physics , composite material , thermodynamics , chemistry , physics
Spherulitic growth rates and physical properties of polysiloxanes are well correlated for a wide range of molecular weights. Below the zero shear entanglement molecular weight, M c , chain folding is probably the norm and fractions are brittle, but after M c is traversed there is a significant decrease in crystallinity, increase in interfacial surface energy and change in lamellar morphology as polymer fractions go from brittle to tough. The chain folded crystallization model with reptation, as a chain folding facilitator, fails to account for this behavior. Appropriate property data for polyethylene and polyisoprene fractions also supports this thesis which now appears to be more of a paradigm than a paradox.