| 摘要 |
Electrical devices comprising PTC elements comprise an oxygen barrier which restricts access of air to the element so that the PTC element absorbs oxygen at a rate less than 10-6 cc/sec/gram. The PTC elements comprise a polymer having dispersed carbon black and an additive which stabilizes the polymer against degradation, especally an organic antioxidant The oxygen barrier may be a layer of a polymeric composition or a self-supporting container principally made of metal and filled with an inert gas.
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