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Characterization of structural heterogeneity of polyurethane coatings
Author(s) -
Paolpi M.,
Lacabanne C.
Publication year - 2001
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.1725
Subject(s) - glass transition , differential scanning calorimetry , polyurethane , dielectric , relaxation (psychology) , amorphous solid , materials science , dynamic mechanical analysis , coating , polymer chemistry , thermal analysis , composite material , thermodynamics , polymer , thermal , crystallography , chemistry , physics , psychology , social psychology , optoelectronics
Abstract The thermal analysis techniques—Differential Scanning Calorimetry and ThermoStimulated Current—have been used to characterize a polyurethane high solid coating. The glass transition temperature, as determined by DSC, is 60°C. Below this glass transition temperature, an α sub dielectric relaxation mode has been observed; it corresponds to cooperative movements precursor of the glass transition. The α ss dielectric relaxation mode, located at ≈ T g has been attributed to movements of soft sequences of the amorphous phase liberated at the glass transition temperature. The analysis of the fine structure shows that they are constituted of elementary processes characterized by relaxation times following a compensation law. Above T g , the α hs dielectric relaxation of hard sequences has been shown. It corresponds to hard sequences hydrogen bonded in polyurethane. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 2786–2790, 2001