Raychem Limited

Marguerite E Deep

Andrew N Au

Stephen M Jacobs

Timothy E Fahey

Nelson H Thein

Hans E Lunk

Donald A Reed

Charles Hill

Conductive polymer compositions, particularly PTC compositions, which contain alumina trihydrate, or another arc-controlling agent, and a lubricant or coupling agent. Advantages which can result from use of the lubricant or coupling agent include improved PTC behavior and improved adhesion to metal conductors, in particular metal foils and solid metal wires.

Conductive polymer devices

Melt-shapeable polymeric compositions comprising a first fluoropolymer of relatively low crystallinity, e.g. a copolymer of tetrafluoroethylene and a perfluorinated comonomer, and a second fluoropolymer of relatively high crystallinity, especially a fluoropolymer obtained by irradiating PTFE or another fluoropolymer which cannot be melt-shaped in the absence of other polymers. The weight ratio of the first to the second polymer is preferably 0.3:1 to 2.5:1. The compositions have a wide variety of uses, for example as insulating materials or, if they contain carbon black or another conductive filler, as PTC conductive polymers.

Melt-shapeable fluoropolymer compositions

Electrical devices containing PTC conductive polymers which have been cross-linked in two steps, preferably by radiation. The conductive polymer is heat-treated above the temperature at which it begins to melt between the two cross-linking steps, and/or the cross-linking steps are such that a center section of the conductive polymer, intermediate the electrodes, is substantially more cross-linked than the conductive polymer adjacent the electrodes. The process is particularly useful for the preparation of circuit protection devices which are subject to high voltage faults.

Electrical devices comprising cross-linked conductive polymers

Conductive polymer compositions

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Los Altos, CA, United States of America

Marguerite E Deep