THE VULCANIZATION OF POLYDIMETHYLSILOXANE RUBBER USING $gamma$-RADIATION (in Russian)
The vulcanization of polydimethylsiloxanes is accomplished by a free- radical mechanism. Results are cited from experimental work conducted to increase the temperature-stability of polymethylsiloxane vulcanizates and to improve their physico-mechanical properties by radiation vulcanization combined with a change in the preparation of the rubber mixture and by introducing new components into the rubber composition. Co/sup 6//sup 0/ with an activity of 1450 g -eq of radium was used as the source. The dose was 0.28 to 0.72 Mr/hr. The characteristic feature of radiation vulcanization appears to be the energy absorbed by the filler, the possibility of further redistribution of the energy by the polymer and the filler, and the formation of a chemical bond between them. Rubbers with satisfactory tensile and elastic properties may be obtained by radiation vulcanization in combination with the introduction of various additives containing powdered silica gel after a lengthy period of thermal sging at 300 deg C. Further refining of the rubber mixture increases the thermal resistance. Radiation vulcanizates of polymethylsiloxane rubber filled with carbon black may be produced with relatively high physicomechanical properties and an elevated thermal resistance. The vulcanizates were current-conducting. Radiation vulcanizates of polymethylsiloxane rubber filled with powdered silica gel and carbon blacks are superior to peroxide vulcanizates in their temperature stability. At a temperature of 200 deg C radiation vulcanizates were obtained with high physico-mechanical properties. The tensile properties of radiation vulcanizates filled with powdered silica gel may be considerably increased by introducing iron oxides or zirconium oxides into the rubber mixture, as well as by preliminary refining. They surpass the corresponding peroxide vulcanizates in their thermal resistance in closed systems at an elevated pressure and are characterized by their higher values of elasticity restoration after various periods of thermal aging, by their lower values of residual compression deformation at 150 to 200 deg C, by a lower weight loss during thermal aging and a somewhat higher frost-resistance. They do not differ from the peroxide vulcanizates in dielectric properties, hardness, elasticity, and tear-resistance. (auth)
- Research Organization:
- All-Union Scientific Research Inst. of Synthetic Rubber im. S.V. Lebedev, USSR
- NSA Number:
- NSA-15-020762
- OSTI ID:
- 4052822
- Journal Information:
- Kauchuk i Rezina, Vol. Vol: No. 9; Other Information: Orig. Receipt Date: 31-DEC-61
- Country of Publication:
- Country unknown/Code not available
- Language:
- Russian
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Related Subjects
COBALT 60
DIELECTRICS
ELASTICITY
FREE RADICALS
GAMMA RADIATION
HARDNESS
HEAT TREATMENTS
HYDROGEN PEROXIDES
IMPURITIES
IRON OXIDES
METHYL RADICALS
POLYMERIZATION
POLYMERS
REACTION KINETICS
RUBBER
SILICON COMPOUNDS
SILICON OXIDES
SILOXANES
THERMAL CONDUCTIVITY
USES
VULCANIZATION
ZIRCONIUM OXIDES