Evaluation of Several Polymer Films for Use as Electrical Insulators

摘要

Samples of polyethylene terephthalate, polycarbonate, polyparabanic acid, polyethersulfone, and polyimide were aged to 32,700 h in SF sub 6 . The temperatures evaluated were 70, 110, 135, and 160 deg C. The influence of aging was determined by post-aging electrical breakdown tests, tensile tests, and density measurements. There was no indication that aging lowered the electrical breakdown voltage. The tensile properties were altered to some extent for all polymers, but large differences in behavior were noted. Density measurements on polyethylene terephthalate showed that the crystallinity of this material increased during aging. Surface crystal growth noted in the scanning electron microscope gave further evidence of morphological changes in this material. Creep tests were run on several polymers: polyethylene terephthalate had the lowest creep strength, and polyimide had the highest. Strain cycle experiments showed that when polyethylene terephthalate and aluminum were bonded together, the high thermal expansion of the aluminum could pull the polymer in two during thermal cycling. (ERA citation 10:049063)