Accession Number : AD0633068

Title :   THERMAL DEGRADATION PROCESSES IN POLYSILOXANES AND THERMAL STABILIZATION BY A CERIUM INHIBITOR,

Descriptive Note : Interim rept.,

Corporate Author : NAVAL RESEARCH LAB WASHINGTON D C

Personal Author(s) : Murphy,C. M. ; Ravner,H. ; Kagarise,R. E.

Report Date : 06 APR 1966

Pagination or Media Count : 26

Abstract : Studies were made of the effect of cerium on the degradation of polyorganosiloxanes (silicones) at 400C in the absence of oxygen. Thermally stressed polydimethylsiloxanes undergo -Si-O bond rupture, initiating anion-propagated degradation to cyclics and linear residues. One-hundred-percent polymethylphenylsiloxanes do not cyclize, but undergo rearrangements leading to crosslinking. In polydimethylsiloxanes, cerium is considered to form active sites which react reversibly with anion fragments, thus limiting further degradation. Cerium has little effect on polymethylphenylsiloxanes, but stabilizes copolymers in direct ratio to the dimethyl content. The excellent response of polydimethyl and lightly phenylated siloxanes to cerium, together with their desirable physical properties, make their use attractive as high-temperature lubricants and hydraulic fluids in selected applications. (Author)

Descriptors :   (*HYDRAULIC FLUIDS, SILOXANES), (*LUBRICANTS, SILOXANES), (*SILICONE PLASTICS, PYROLYSIS), (*SILOXANES, STABILIZATION), THERMAL STABILITY, LUBRICANT ADDITIVES, CERIUM, CHEMICAL REACTIONS, HEAT RESISTANT MATERIALS

Subject Categories : Organic Chemistry
      Lubricants and Hydraulic Fluids
      Plastics

Distribution Statement : APPROVED FOR PUBLIC RELEASE