Polymer compositions exhibiting a PTC property and methods of fabrication
First Claim
1. A conductive polymer composition exhibiting a positive temperature coefficient (PTC) property, the composition comprising:
- a matrix comprising at least one polymer component; and
a plurality of conductively clad microspheres dispersed within the at least one polymer component, each conductively clad microsphere comprising an electrically conductive cladding over a core portion, wherein the plurality of core portions has a bulk density of less than about 2.0 g/cm3 and wherein the plurality of conductively clad microspheres comprises at least about 20% by volume of the composition.
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Accused Products
Abstract
Various embodiments of the invention provide polymeric compositions including PTC composites that exhibit highly non-linear PTC effects together with extremely rapid, repeatable switching within a predetermined temperature range. In one embodiment, the polymer composite includes a polymer base material with dispersed conductive particles that have very low densities and very low thermal conductivity properties. The conductive particle component can comprise hollow glass microspheres to provide low mass and low thermal conductivity properties together with a nanoscale conductive cladding of silver or gold. The conductively clad microspheres have a core portion with a bulk density of less than about 2.0 g/cm3 and a mean thermal conductivity of less than about 5.0 W/m-° K.
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Citations
22 Claims
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1. A conductive polymer composition exhibiting a positive temperature coefficient (PTC) property, the composition comprising:
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a matrix comprising at least one polymer component; and a plurality of conductively clad microspheres dispersed within the at least one polymer component, each conductively clad microsphere comprising an electrically conductive cladding over a core portion, wherein the plurality of core portions has a bulk density of less than about 2.0 g/cm3 and wherein the plurality of conductively clad microspheres comprises at least about 20% by volume of the composition. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A conductive polymer composition exhibiting a positive temperature coefficient (PTC) property, the composition comprising:
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a matrix comprising at least one polymer component; and a plurality of conductively clad glass microspheres dispersed within the at least one polymer component, each condictively clad glass microsphere comprising an electrically conductive cladding over a core portion, wherein a plurality of core portions has a mean thermal conductivity of less than about 5.0 W/m.-°
K. - View Dependent Claims (14, 15, 16, 17)
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18. A conductive polymer composition exhibiting a PTC property, the composition comprising:
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a matrix comprising at least one polymer component comprising at least one of polyethylene, polyamide, polystyrene, polyacrylonitrile, polyethylene oxide, polyacetal, thermoplastic modified cellulose, polysulfone, thermoplastic polyester, poly(ethyl acrylate), poly(methyl methacrylate), nylon, polyvinylidene fluoride or ethylene tetrafluoroethylene; and a plurality of conductively clad elements dispersed within the at least one polymer component, the plurality of elements comprising at least about 20% by volume of the composition, each element comprising an electrically conductive cladding portion over a core portion, wherein the plurality of core portions has a bulk density of less than about 2.0 g/cm3 and the cladding portion comprises at least one of silver, gold, platinum, nickel, tin, copper, palladium, magnesium, aluminum, iron, molybdenum, tungsten, tantalum, zirconium, zinc, cobalt, chromium or carbon. - View Dependent Claims (19, 20, 21, 22)
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Specification