Characterization of polyurethane network elastomers

Polyester urethane network elastomers with incorporated hard segment oligomers have been prepared by poly(ethylene adipate)glycol (PEA), 2,4‐tolylene diisocyanate (TDI), and 1,4‐butanediol (BD). These hard segment oligomers were hydroxy‐terminated oligomers ([BD‐TDI]n‐BD; n=1,3), obtained by reacting BD with TDI. Concentrations of allophanate as a cross‐linking site were determined by the amine degradation method. Hard segment moieties were obtained by a novel selective hydrolysis of soft segments in the elastomers. Molecular weight distributions of hard segment were measured by means of GPC. Mechanical and thermal properties were measured. Dependence of rubber elasticity on physical cross‐linking between normal elastomers and the elastomers with incorporated hard segment oligomers were discussed.