PROPERTIES OF ELASTOMERIC POLYURETHANES OBTAINED WITH EPSILON-CAPROLACTONE MACROGLYCOL

Three elastomeric polyurethanes were obtained by reacting MDI (dipheny lmethane-4,4'-diisocyanate) with epsilon-caprolactone macroglycols of different molecular weight (1000-3000 daltons); the chain extender use d was 1,4-butane diol. The increase in the molecular weight of the mac roglycol modified the degree of phase separation and the interactions between the hard and soft domains in the polyurethane structure. The p roperties of elastomeric polyurethanes were studied by using Gas Perme ation Chromatography, FTIR spectroscopy, DSC, DMTA, rheology (stress-c ontrolled rheometer), contact angle measurements, and T-peel strength tests. The use of low molecular weight macroglycol produced polyuretha ne with small crystallinity, relatively higher T-g and reduced softeni ng enthalpy. Therefore a poor degree of phase separation was produced and reduced mechanical and viscoelastic properties were obtained. On t he other hand, a high molecular weight macroglycol improved the degree of phase separation producing better mechanical, viscoelastic and the rmal properties in the polyurethanes. Furthermore, the increase in mol ecular weight of macroglycol increased the adhesion of PVC/polyurethan e adhesive joints and further changed the locus of failure. (C) 1997 E lsevier Science Ltd.