Dynamics of polyurethane elastomers by muon spin relaxation

Muon spin relaxation has been used to study the dynamics of hard domains in three polyurethane elastomers based on methylenediphenyleneisocyanate. Rep olarisation curves of the muonium spin show the muon implants to the aromat ic ring of the hard segments. Qualitative changes in the muon spin relaxati on rate indicative of phenyl ring dynamics can be seen as the polyurethane is heated from 100 to 470 K. Interpretation of the changes seen in the muon spin relaxation rate are hampered by the absence of a detailed theoretical understanding. Further, poor muon counting statistics of this initial expe riment make an accurate analysis impossible. (C) 2000 Elsevier Science Ltd. All rights reserved.