STRUCTURE AND PROPERTIES OF SILOXANE-CONT AINING URETHANE POLYMER NETWORKS

The morphology, phase composition, and relaxation spectra of a series of siloxaneurethane polymer networks were examined as a function of th e chemical nature of junctions and of the length of interjunction frag ments. The study was conducted using dynamic mechanical and dielectric spectroscopies, X-ray diffraction, and electron microscopy. It was fo und that in polysiloxaneurethanes, relatively short (6 - 21 siloxane u nits) linear dimethylsiloxane fragments (soft blocks) were segregated to form an organosilicon phase, whereas short diisocyanate fragments ( rigid blocks) formed microdomains, which performed as junctions of the physical network. Films with good mechanical properties were obtained .