A STUDY OF ALIPHATIC POLYURETHANE ELASTOMERS PREPARED FROM DIISOCYANATE ISOMER MIXTURES

Linear polyurethane elastomers are block copolymers which are elastomeric because they are phase separated. The soft block is derived from a hydroxy terminated telechelic polymer, frequently a polyether or polyester of a molecular weight less than 3000 and a glass transition temperature well below room temperature. The hard block, having a T//g above room temperature, consists of a diisocyanate and a diol. This paper reports the study of the isomer composition of the diisocyanote and the effect of isomer composition on the properties of the elastomers. Mixtures of the isomers varying from approximately 10% of the trans-trans isomer up to 95% (t-t) have been prepared and the properties of polyurethanes prepared from them have been studied.