Diffusion as a probe to assess stretching‐induced morphological changes in polyurethane

An analysis of the diffusion of toluene through polyurethane based on bis (p‐cyclohexyl diisocyanate), poly(tetramethylene glycol) 1000, and 1,4‐butane diol, subjected to varied degrees of elongation by stretching, is presented. The diffusion coefficient is increased by 60% in polymers drawn to 200% and above. Beyond 400% elongation, the diffusion coefficient attained a constant value. Associated changes are observed in the wide‐angle x‐ray diffraction pattern. These diffusion and x‐ray changes are correlated with restructuring of the polymer induced by stretching.