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The effect of average soft segment length on morphology and properties of a series of polyurethane elastomers. I. Characterization of the series
Author(s) -
Martin Darren J.,
Meijs Gordon F.,
Renwick Gordon M.,
Mccarthy Simon J.,
Gunatillake Pathiraja A.
Publication year - 1996
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/(sici)1097-4628(19961128)62:9<1377::aid-app7>3.0.co;2-e
Subject(s) - materials science , differential scanning calorimetry , shore durometer , small angle x ray scattering , thermoplastic elastomer , elastomer , composite material , dynamic mechanical analysis , polyurethane , ultimate tensile strength , thermoplastic polyurethane , glass transition , morphology (biology) , polymer chemistry , polymer , copolymer , scattering , physics , genetics , biology , optics , thermodynamics
A series of eight thermoplastic polyurethane elastomers were synthesized from 4,4′‐methylene diphenyl diisocyanate (MDI) and 1,4‐butanediol (BDO) chain extender, with poly(hexamethylene oxide) (PHMO) macrodiol soft segments. The soft segment molecular weights employed ranged from 433 g/mol to 1180 g/mol. All materials contained 60% (w/w) of the soft segment macrodiol. Differential scanning calorimetry (DSC), dynamic mechanical thermal analysis (DMTA), wide angle x‐ray diffraction (WAXD), and small angle x‐ray scattering (SAXS) techniques were employed to characterize morphology. Tensile and Shore hardness tests were also performed. Materials were tested in the annealed state. It was found that an increase in segment length was accompanied by an increase in the degree of microphase separation, average interdomain spacing, hard domain order, hardness, stiffness, and opacity. DSC experiments showed the existence of several hard segment melting regions that were postulated to result from the disordering or melting of various hard segment length populations. For the system and composition ratio employed, it was found that optimum tensile properties (UTS and breaking strain) were achieved when a PHMO molecular weight of between 650 and 850 was utilized. © 1996 John Wiley & Sons, Inc.