| 摘要 |
A method of annealing a PTC conductive polymer composition comprising a mixture of two crystalline polymers. Compositions having improved electrical characteristics are obtained by annealing at a temperature between the melting points of the two polymers, preferably closer to the melting point of the lower melting polymer. Particularly useful results are obtained when the annealing method is applied to a self-limiting heater in which the PTC core comprises carbon black dispersed in a mixture of polymers, one of which has a melting point of at least 160 DEG C., preferably at least 200 DEG C., e.g. a mixture of polyvinylidene fluoride and an ethylene/tetrafluoroethylene copolymer.
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