MECHANOOPTICAL PROPERTIES AND STRUCTURE OF SEGMENTED URETHANE-UREA BLOCK COPOLYMERS

Mechanooptical properties of segmented urethane-urea block copolymers on the base of THF, propylene oxide, ethylene diamine and rigid 4,4'-diphenylmethane diisocyanate (MDI) block have been studied in films by birefringence method. Very high birefringence being a result of microphase separation of components and formation by MDI rigid blocks of domains with presumable MDI chains orientation being perpendicular to the longest axis was observed. The number of these chains in domains was evaluated. The average MM of a domain is above 7000, their linear dimensions are equal to 3-4 nm. Two regions of relaxations transitions were observed. For T is similar to 170-degrees the decay of the percolational cluster and formation of relatively independent domains consisting of rigid MDI blocks were shown. At T > 250-degrees the <<melting>> of domains proceeding in the narrow temperature range for all samples was observed.