Low frequency elastic modulus measurements on segmented ester polyurethanes

Low frequency extentional modulus measurements are reported as a function of temperature on a series of low isocyanate containing segmented ethyleneadipate diphenyldiisocyanate elastomers. The effects of variation of isocyanate content, molecular weight of the ester block and the ratio of 1, 3 to 1, 4 butanediol chain extender on the glass transition temperatures of the ester phase are explored. The mobility of the ester phase appears to reflect the degree of perfection of the organisation of the urethane phase. The plateau modulus similarly exhibits a correlation with the perfection of the hard phase packing and this is also reflected in the variation of the effective crosslink density obtained from swell measurements. The detailed organisation appears from this study to influence the degree of mobility of the ester phase.