Study of dielectric relaxation in polymer semi-interpenetrating networks based on toluylene diisocyanate and propylene sulphide☆

Abstract The authors have studied dielectric relaxation in semi-interpenetrating polymer networks based on 2,4-toluylene diisocyanate and propylene sulphide with variation in the composition from 0–100%. The temperature curves of dielectric absorption reveal regions of relaxation of dipole polarization associated with the segmental mobility of the macromolecules of polypropylene sulphide in the segregated phase and in the transitional layer. The composition with 70–73% polypropylene sulphides is “critical” since the characteristics of dielectric relaxation become discontinuous at this composition. It is postulated that the given concentration of the polypropylene sulphide corresponds to inversion of the phase structure. The phase of the polytoluylene diisocyanate component forming the spatial mesh, continuous at lower concentrations of polypropylene sulphide, becomes discontinous for a content of polypropylene sulphide 70–73% and the volume of the transitional layer sharply decreases.