Abstract
When the recipe is basically the same, different polymers differ in dynamic rate and damping. Ethylene—propylene terpolymer, SBR, neoprene, and butyl gave higher dynamic rate and higher damping than natural rubber, polyisoprene, and the blend of polyisoprene and cis 1,4-polybutadiene. The lowest dynamic rate and lowest damping is obtained with polyisoprene. At room temperature, polymers having the highest damping also have the largest ratio of dynamic to static rate. One cannot predict the effect of temperature on dynamic rate by measuring static rate at these temperatures. Increase in temperature lowers dynamic rate, decrease in temperature increases it. This effect was least with a blend of polyisoprene and cis 1,4-polybutadiene, closely followed by polyisoprene, and natural rubber. The largest change was with butyl. Dynamic rate increases with time after cure. After 26 hr, dynamic rate is a function of the logarithm of time. This effect is least with polyisoprene. Natural rubber, SBR, EPT, neoprene and a blend of polyisoprene with cis 1,4-polybutadiene all follow Equation (1). Butyl has, by far, the greatest change in dynamic rate with time. Reducing the deflection from 0.012 in. to 0.004 in. linearly increased the dynamic rate. Times of vibration between 2 minutes and 60 minutes at room temperature had no effect on dynamic rate.
Effect of Temperature on Space Charge Distribution of Oil–Paper Insulation under DC and Polarity Reversal Voltage
