PHASE STATE AND MOLECULAR MOBILITY OF SEG MENTED POLYURETHANES

Spin-lattice and spin-spin NMR relaxation was studied in a series of s egmented polyurethanes based on poly(diethylene glycol adipate), 2,4-t olylene diamine, and 2,4-toluene diisocyanate. It was concluded that N MR relaxation is determined by physical interactions between rigid blo cks and also between rigid and flexible blocks. The dependence of the degree of segregation on the molecular weights of rigid and flexible b locks was determined, A quite high degree of segregation in the invest igated systems and the related manifestations of individual features o f flexible blocks enabled to follow the dynamics of the molecular chai n with fixed end and study variation of the glass transition temperatu re and the activation energy of the segmental motion of this chain as a function of its molecular weight.