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Study of critical phenomena of polystyrene—poly(vinyl methyl ether) blends by solid state NMR
Author(s) -
Chu C. W.,
Dickinson L. C.,
Chien James C. W.
Publication year - 1990
Publication title -
journal of applied polymer science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.575
H-Index - 166
eISSN - 1097-4628
pISSN - 0021-8995
DOI - 10.1002/app.1990.070410933
Subject(s) - polystyrene , materials science , spin diffusion , miscibility , polymer blend , relaxation (psychology) , phase (matter) , ether , spin–lattice relaxation , polymer chemistry , phase diagram , atmospheric temperature range , copolymer , analytical chemistry (journal) , diffusion , proton , thermodynamics , polymer , chemistry , organic chemistry , composite material , physics , psychology , social psychology , quantum mechanics
Thermally induced phase separation in PS/PVME blends was studied by solid state NMR. The proton spin—lattice relaxation in both the laboratory and the rotating frame were measured for the entire range of blend composition. Under conditions in which the blends are said to be compatible by other techniques T 1 p Hresults obtained at −5°C showed microheterogeneity at a 10−°A scale. T 1 p H values at room temperature are closer to the longer relaxation time of PS than that expected from simple weighted average of the relaxation times of the constituent homopolymers. This indicates incomplete averaging by spin diffusion and a restraining effect of PS on segmental motions of PVME. The blends were heated to cause phase separation and quenched. From the biphasic decay of 13 C magnetization, the compositions of the separated phases were estimated to give a lower critical solution temperature phase diagram. NMR relaxation in PVME blends with PS molecular weights of 9, 100, and 900 K were compared.