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The effect of annealing on the thermal and dynamic mechanical properties of para‐tetramethyl xylene diisocyanate‐based polyurethanes
Author(s) -
Stack G. M.,
Beumel L. L.
Publication year - 1992
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.1992.070440215
Subject(s) - materials science , melting point , dynamic mechanical analysis , annealing (glass) , dissipation factor , polyurethane , composite material , glass transition , enthalpy of fusion , enthalpy , polymer chemistry , thermodynamics , polymer , dielectric , physics , optoelectronics
A series of polyurethane elastomers based on the para‐Tetramethyl Xylene diisocyanate group were annealed at temperatures from 100 to 180°C. These high‐temperature exposures were found to raise significantly the peak melting point of the urethanes that contained crystalline hard segments. The corresponding enthalpy of fusion was found to decrease after annealing at the higher temperatures. In most cases, the annealings caused a slight increase in the soft‐segment glass transition temperature, indicating that some increase in phase mixing had occured. Dynamic mechanical measurements indicated that the annealings caused a slight reduction in the Young's modulus and a broadening of the loss–tangent peak. The broadening of the loss–tangent peak can be attributed to the increased phase mixing induced by the annealings. The large increases in melting point induced by annealing do not appear to significantly affect the subsequent dynamic mechanical properties.