It is examined the influence of diisocyanate’s small addings on mechanical properties of polymer mixes (chlorsulfurized polyethylene – triple ethylene-propylene rubber). It is held the appraisal of structural and solid characteristics of raw and vulcanized polymer mixes and shown that the observed improvement of individual polymers and their mixes qualities after isocyanate’s introduction into the system is a response of compositions consisting of components with close meanings of solubility parameters on process of their saturation by relatively polar olygomers (low molecular weight polymers). Observed transformations of structure and phase content of vulcanized modified polymers mixes are due to macromolecules` degree of branching and polarity growth, which increase their degree of compatibility and packing.