Abstract: Conductive polymer compositions which exhibit PTC behavior comprising a first polymeric component which may be crystalline, a second component, and a particulate conductive filler. The second component may comprise either a polymer which exhibits side chain crystallization or a crystalline material which has a sharp melting point and has poor physical properties at room temperature and/or exhibits no melt strength at elevated temperatures. The compositions are particularly useful in electrical devices which exhibit "square" resistance vs. temperature characteristics.

Abstract: A polymer blend comprises (A) a fluorinated ethylene-propylene copolymer and (B) a fluoroelastomer. The fluoroelastomer comprises a block copolymer comprising at least one elastomeric segment comprising tetrafluoroethylene, vinylidene fluoride, and hexafluropropylene repeat units in a mole ratio 45-90:5-50:0-35 and at least one nonelastomeric segment comprising tetrafluoroethylene and ethylene repeat units. The weight per cent of copolymer (A) relative to the combined weights of copolymer (A) and fluroelastomer (B) is between about 70% and about 97% or between about 3% and about 30%.