Thermal Aging

In Japan, study on thermal aging of insulating materials and investigation of testing methods for thermal endurance were begun by T. Akahira's pioneering theoretical and experimental work in 1925. From 1957, Y. Saito and his co-workers had published papers describing a short-time testing method for thermal endurance by mass spectrometry. A new theory and method for analyzing thermal analysis were founded by T. Akahira and T. Sunose, while another theory and method were set forth by T. Ozawa. These theories, which are applied to results obtained under changing temperature conditions, have contributed comparison of test results obtained at different temperatures by conventional testing method and also to analyze the aging phenomena under changing temperature that is near to actual conditions. In general, thermal aging is affected by concentrations of oxygen and products in the reaction region. Therefore, there are attempts to elucidate diffusion phenomena in aging reactions. These studies have been progressing by mutual influence, and will do so in the future.