RADIATION VULCANIZATION OF HETEROSILOXANE RUBBERS

Vulcanizates with the best physicomechanical properties (tensile strength, 34 - 133 kg/cm/sup 2/; elongation, 80 -150%; residual elongation, 3-4%) were produced by gamma irradiation (doses, 2.2-5.6 Mr) of 0.15% vinyl group- containing heterosiloxane rubber mixes containing compounds of polyvalent metals STAunspecified! and filled with Aerosil, under vacuum. The heat resistance of radiation vulcanizates of the heterosiloxane polymers considerably surpassed that of radiation vulcanizates of pure or vinyl group-containing polydimethylsiloxanes (SKT and SKTV rubbers). Vulcanizates produced by gamma irradiation in air of polyborophosphorosiloxane rubber mixes containing polyvalent metal compounds and Aerosil retained satisfactory physicomechanical properties after heat aging in air for 3 hr at 400 deg C or 5 min at 430 deg C, or in the absence of air for 1.5 hr at 450 deg C, 40 mid at 500 deg C, or 5 min at 570 deg C. The enhanced heat resistance of polyheterosiloxane vulcanizates can be attributed to the stopping, by hetero atoms, of degradation by the free radical chain mechanism at 390--420 deg C or to intramolecular stabilization by hetero atom-containing groups of reactive intermediate products formed during heat aging. Radation vulcanizates of heterosiloxane polymers exhibited good low-temperature and radiation resistance and retained their hardness after heatmore » aging in the absence of air. They are characterized by autohesion and by high adhesion to metals (4.4--5.4 kg/ cm/sup 2/). (TCO)« less