Tracking degradation and pyrolysis of EPDM insulators

EPDM (ethylene-propylene-diene terpolymer) rubber insulators were subjected to tracking resistance tests. Gases evolved in these tests were collected and analyzed by gas chromatography and Fourier-transform infrared spectrophotometry. Gases obtained by pyrolysis of this rubber compound (at 400, 600, 800, 1000 degrees C) were also collected and analyzed. Comparison of the gaseous mixtures obtained in both cases revealed that they are similar: CO, CO/sub 2/ ethene, and methane are their major components. Acetylene was also obtained in tracking degradation experiments, probably due to methane reactions in the high-temperature tracking plasma. These results show that pyrolysis is the major event leading to gaseous product formation in tracking degradation.<
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