Life Characteristic and Life Estimation of Paper Based Phenolresin Laminates

Abstract

Life characteristic of the paper based phenolresin laminates was investigated using test samples thermally deteriorated in oil. In addition to a conventional study of static tensile sterength, effects of repetitive stress were also examined.
The test results revealed a change in deterioration mechanism of the paper based phenolresin laminates at about 170°C while its life time by thermal only deterioration remained very long. The tests on repetitive tensile stress yielded the following characteristic: the slope of S-N curve has a trend to become more flat as the heat deterioration of the samples aggravates and the breaking strength after a duration of tensile stresses tends to converge at about 20% of the strength of new materials.
Moreover, a good correlation between tensile strength and hardness was obtained. With the use of the life expectation curve obtained from the tests on both static and repetitive tensile strength, it becomes possible to estimate life time in actual operating conditions.