Abstract: Electrical devices which comprise a PTC element composed of a PTC conductive polymer composition and a contiguous CW element composed of a conductive polymer composition which comprises an organic thermoplastic polymer and a conductive carbon black having a particle size (D) in millimicrons and surface area (S) in m2/g such that S/D is at least 10. D is preferably less than 27 millimicrons, especially less than 18 millicrons. S/D is preferably at least 12, especially at least 18. Particularly useful devices are in the form of heaters.

Abstract: A liquid crystal apparatus including a low birefringence encapsulated liquid crystal material in a containment medium. The liquid crystal material contains a dye that conforms to the structure of the liquid crystal material. The difference between the ordinary index of refraction and extraordinary index of refraction of the liquid crystal material is between about 0.050 and 0.115. The index of refraction of the containment is greater than the ordinary index of refraction of the liquid crystal material. The liquid crystal apparatus provides low haze at off-axis viewing angles, permits efficient sine-wave power operation, and provides energy control.

Abstract: A liquid crystal apparatus including a low birefringence encapsulated liquid crystal material in a containment medium. The difference between the ordinary index of refraction and extraordinary index of refraction of the liquid crystal material is between about 0.050 and 0.115. The index of refraction of the containment is greater than the ordinary index of refraction of the liquid crystal material. The liquid crystal apparatus provides low haze at off-axis viewing angles and permits efficient sine-wave power operation.

Abstract: Conductive polymer compositions based on polyvinylidene fluoride have improved properties when the polyvinylidene fluoride has a very regular structure which can be characterized by a low head-to-head content in the repeating units. The improved properties include electrical stability when contacted by organic fluids and/or when maintained at elevated temperatures in air. Such compositions which exhibit PTC behavior are particularly useful in the form of self-limiting heaters which are immersed in organic fluds, especially flexible strip heaters for heating diesel fuel before it passes through a fuel filter.

Abstract: Conductive polymer compositions based on polyvinylidene fluoride have improved properties when the polyvinylidene fluoride has a very regular structure which can be characterized by a low head-to-head content in the repeating units. The improved properties include electrical stability when contacted by organic fluids and/or when maintained at elevated temperatures in air. Such compositions which exhibit PTC behavior are particularly useful in the form of self-limiting heaters which are immersed in organic fluids, especially flexible strip heaters for heating diesel fuel before it passes through a fuel filter.

Abstract: 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.

Abstract: The resistivity/temperature characteristics of PTC conductive polymers which have little or no cross-linking can be modified by stretching. The rate at which resistivity rises with temperature is increased, and the peak resistivity is decreased; however, the decrease in peak resistivity is substantially smaller than that observed with PTC conductive polymers having a high degree of cross-linking. Therefore, heat-recoverable electrical devices, particularly for covering telephone and other cable splices, comprise (a) a layer of a PTC conductive polymer which has little or no cross-linking, (2) an adjacent heat-recoverable layer of a PTC or ZTC conductive polymer which has a relatively high level of cross-linking, and (3) electrodes which can be connected to a power supply so that current passes through the layers and causes recovery of the device; preferably an uncrosslinked PTC layer is sandwiched between two cross-linked ZTC layers. Non-recoverable devices, e.g.

Abstract: 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.

Abstract: Electrical devices which comprise a PTC element composed of a PTC conductive polymer composition and a contiguous CW element composed of a conductive polymer composition which comprises an organic thermoplastic polymer and a conductive carbon black having a particle size (D) in millimicrons and surface area (S) in m.sup.2 /g such that S/D is at least 10. D is preferably less than 27 millimicrons, especially less than 18 millimicrons. S/D is preferably at least 12, especially at least 18. Particularly useful devices are in the form of heaters.