Raychem Limited

Len Barrett

James A Rinde

Neville S Batliwalla

Norman A Gac

Curable compositions which are useful for encapsulating electrical connections and for joining metals to metals, and which comprise a mixture of high and low molecular weight fluorocarbon elastomers. Preferred compositions comprise a mixture of three fluorocarbon elastomers, the first having a Mooney viscosity at 121.degree. C. of at least 120, the second a Mooney viscosity at 121.degree. C. of 80 to 110, and the third a Brookfield viscosity at 100.degree. C. of 1,000 to 4,000 centipoises, in amounts 5 to 50%, 25 to 70% and 5 to 50% respectively, based on the weight of the polymeric component. The compositions can be easily molded under heat and pressure, and after they have been cured, they have remarkable resistance to degradation by hot liquids, even under pressure. Consequently, the compositions are very useful in the manufacture of self-regulating heaters for use in heating the production tubes of oil wells.

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San Jose, CA, United States of America

Len Barrett