| 摘要 |
A conductive polymer composition exhibiting PTC behavior and the method of making the composition are disclosed. The composition includes a particulate conductive filler and a polymeric portion. The polymeric portion contains a volume-expansion-regulating high molecular weight polymer, such as ultra high molecular weight polyethylene (UHMWPE), that resists melting and causes an increase in the volume of the composition, upon heating, but migrates minimally within the composition. The high molecular weight polymer preferably has a linear thermal expansion coefficient of at least 200x10-6/ DEG C. The polymeric portion also contains a melt-extrudable polyolefin matrix in which the conductive filler and the high molecular weight polymer are dispersed. The high molecular weight polymer is present in an amount which allows the final composition to be melt-extrudable. An electrical device containing a PTC element that utilizes the novel composition and at least two electrodes is also disclosed. The resulting materials are applicable to switch devices, self-limiting heaters, EMI, ESD, utility, and telecommunications components.
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