Accession Number : AD0807340

Title :   ELASTOMERIC AND MECHANICAL PROPERTIES OF POLY-M-CARBORANYLENE SILOXANES, III.

Descriptive Note : Technical rept.,

Corporate Author : PRINCETON UNIV NJ FRICK CHEMICAL LAB

Personal Author(s) : Zaganiaris, Emmanuel J. ; Sperling, Leslie H. ; Tobolsky, Arthur V.

Report Date : JAN 1967

Pagination or Media Count : 27

Abstract : Stress relaxation properties of SiB-2 and poly(dimethyl siloxane) were compared in air and pure nitrogen. The effect of a protective filler system was also investigated. Within the framework of the present experiments, SiB-2 exhibits greater stability than poly(dimethyl siloxane) at elevated temperatures, retaining useful properties after 24 hours in air at 260C in the absence of protective filler. As expected, use of a nitrogen atmosphere, protective filler, or both raise the maximum useful temperature significantly. The crystalline structure of SiB-2 was investigated by x-ray techniques and force-temperature experiments. The thermodynamic melting point was found to be 66C, and qualitative information was obtained on the crystallite size distribution. The physical properties of SiB-1 were investigated by modulus-temperature methods. This polymer was highly crystalline. The second-order transition occurred at 25C, and melting at 240C. Above this temperature, SiB-1 exhibited a characteristic rubbery plateau, which terminated at 355C when oxidative crosslinking became significant. SiB-1 appears to be significantly more stable than SiB-2 at elevated temperatures. It seems likely that a copolymer may exhibit properties superior to either, and it is recommended that several compositions be prepared and investigated. (Author)

Descriptors :   (*SILOXANES, HIGH TEMPERATURE), (*SYNTHETIC RUBBER, THERMAL STABILITY), ESTERS, BORIDES, NITROGEN, AIR, MELTING POINT, CRYSTAL STRUCTURE, CROSSLINKING(CHEMISTRY), THERMAL STRESSES, OXIDATION, COPOLYMERIZATION, SILICONE PLASTICS, BORANES, CARBON COMPOUNDS, WATER VAPOR, CONTROLLED ATMOSPHERES, REACTION KINETICS, .

Subject Categories : Elastomers and Rubber

Distribution Statement : APPROVED FOR PUBLIC RELEASE