Raychem Limited

Wendell W Moyer

Robert Smith-Johannsen

Bernard J Lyons

David A Horsma

Nelson M Shen

Eugene F Lopez

Christian A Debbaut

Lester T Toy

Peter H Van Konynenburg

John P Arrington

Stephen F Powell

Andrew V Brown

Norman A Gac

Patrick K Tsou

David R Myers

Patrick M Martens

David E James

David Terrell

The present invention provides polymerizable compositions which may be cured with ultraviolet light to form polymer compositions which are especially useful as channel optical waveguides. In particular, they exhibit stability at elevated temperatures such as occur in, for example, reflow soldering.

Curable compositions and methods for use in forming optical waveguide

An article suitable for use in the adhesive joining of two optical fibers with low light loss comprises a tubular container an inner surface of which is coated with a release agent and/or is composed of an inherently releasing material, which is larger in cross-section at the ends than at a central region, the smaller central region being where the ends of the fibers are joined.

Optical fiber adhesive joint tube

A temperature indicating composition is provided for use on recoverable articles so that heating to produce recovery or to activate a heat-activatable sealant can be monitored. The composition comprises a thermochromic colorant in a binder and an activator that causes the thermochromic colorant to change color at a temperature lower than the temperature at which the colorant would change temperature in the absence of the activator. The thermochromic colorant can be folic acid and the activator can be an acid that has a pK of less than 4.2.

Thermochromic composition

A splice between two multiconductor cables is protected from ingress of water by a closure which is filled with an expanding foam sealant which provides pressure inside the closure sufficient to force the sealant into the interstices of the splice and the interstices between the conductors in the cable, which pressure is retained in the closure until the sealant cures or hardens.

Protection of cable splice

Novel conductive polymer compositions which exhibit useful PTC behavior are produced by cross-linking processes. By correlating the polymer, the conductive filler dispersed therein, and the cross-linking conditions, PTC compositions having desired resistance/temperature characteristics can be prepared. In particular the cross-linking can be carried out so as to provide compositions having a switching temperature around the cross-linking temperature. The invention is applicable to both elastomeric and thermoplastic polymers, and provides for the first time a method of making PTC compositions exhibiting useful PTC behavior from elastomers.

PTC Compositions and devices comprising them

Conductive polymer compositions which have improved voltage stability and which preferably exhibit PTC behavior. The compositions comprise a carbon black dispersed in a crystalline copolymer of an olefin and at least 10% by weight of an olefinically unsaturated comonomer containing a polar group. The carbon black has a particle size greater than 18 millimicrons, preferably greater than 30 millimicrons, a d-spacing greater than 360 and a surface area which is less than

Conductive polymer compositions, and to devices comprising such

Expansive cement compositions and novel expansion agents containing free lime for use in such compositions. The expansion agents are prepared by heating lime of particle size less than 250 microns in an atmosphere comprising water vapor at 100.degree. to 400.degree. C. or carbon dioxide at 350.degree. to 850.degree. C., or by heating a partially hydrated lime at a temperature of at least 100.degree. C. The encapsulated limes produced in this way are useful as expansion agents in hydratable cement compositions, the amount thereof generally being less than 30%, preferably 3 to 10%, based on the weight of the cement and additive. Cement compositions containing the novel expansion agents are useful in a wide variety of uses where shrinkage of the composition on drying has to be prevented or reduced.

Expansive cement and agent therefor

Disclosed is a process of coating discrete, unagglomerated particles of less than 20 microns with a high polymer coating, and compositions such as conductive compositions using such coated particles. The particles are coated with the polymer in a fluid energy mill such that substantially uniform coated particles are obtained which are free-flowing, non-agglomerative and readily dispersable in a suitable binder.

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Atherton, CA, United States of America

Wendell W Moyer