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Thermoplastic urethane elastomers. II. Effects of variations in hard‐segment concentration
Author(s) -
Seefried C. G.,
Koleske J. V.,
Critchfield F. E.
Publication year - 1975
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.1975.070190913
Subject(s) - polycaprolactone , glass transition , elastomer , materials science , thermoplastic elastomer , polymer , polyester , copolymer , polymer chemistry , diol , thermoplastic , composite material , rheology , methylene , transition temperature , chemistry , organic chemistry , superconductivity , physics , quantum mechanics
The dynamic mechanical properties of thermoplastic urethane elastomers have been charac‐terized for polymers composed of varying hard‐segment concentrations and for two different molecular weight polyester diols as soft segments. The urethane polymers based on an 830 M̄ n polycaprolactone diol exhibited a progressive increase in glass transition temperature at increased levels of hard segments. In contrast, a similar series of polymers prepared with a 2100 M̄ n polycaprolactone diol as the soft segment maintained a relatively constant glass transition temperature. These differences are attributed to the relative degree of phase separation between the constitutive blocks of the copolymer. The polymers of both series possessed two lower‐temperature, secondary relaxations, which are ascribed to methylene sequence mobility within the polycaprolactone units and to possible disruption of interfacial associations between the hard‐ and soft‐segment structures.