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Non equilibrium annealing behavior of poly(vinyl acetate)
Author(s) -
Bair H. E.,
Johnson G. E.,
Anderson E. W.,
Matsuoka S.
Publication year - 1981
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.760211410
Subject(s) - vinyl acetate , enthalpy , materials science , annealing (glass) , glass transition , dielectric , polymer , thermodynamics , bound water , relaxation (psychology) , polymer chemistry , polyvinyl acetate , composite material , organic chemistry , chemistry , molecule , psychology , social psychology , physics , optoelectronics , copolymer
The water absorbed by poly(vinyl acetate), PVAc, at 23°C was found in two states. The first, which can account for up to 4 weight percent, was bound to the polymer. The second was in a freezable or clustered form. The latter type of water had no effect on PVAc's glass temperature, whereas, the former kind plasticized T g . In annealing studies, the enthalpic and dielectric response of PVAc when held at a fixed temperature increment, Δ T , below T g , was observed to be independent of the amount of bound water. The time dependence of the shift in the dielectric relaxation spectrum and the recovery of the enthalpy towards its equilibrium value as PVAc approached its equilibrium glassy state from a lower temperature as compared to a higher temperature was initially slower. This delayed response to expansion was of the order of the polymer's average relaxation time at the lower temperature. A model was proposed to explain this asymmetric behavior based upon changes in the polymer's free volume as well as its occupied volume.