建築用ゴム系材料のオゾン試験における力学的負荷条件の考察

概要

論文の詳細を見る
An ozone tester, equipped with apparatuses measuring either stress relaxation of specimens at constant strain or creep of them at constant stress, was made in order to investigate differences of ozone degradation caused by different loading conditions. Sheets of butyl rubber blended with EPDM in three levels were specially made in this study. Mechanical property of the sheet with each mix were varied by the degree of vulcanization. At first step, the specimens were exposed to ozone in the ozone tester controlled at a concentration of 50 pphm at 40℃, and stresses or strains of them were recorded during the test. The specimens were periodically inspected with cracks or ruptures if any. Good ozone resistance was observed with lower vulcanized samples in the test with constant strain, on the contrary, was observed with higher vulcanized samples in the test with constant stress. The results obtained were considered to depend on the visco-elastic behavior of samples, then a new factor expressing loading levels, an average of apparent strain energy, which can be obtained by integrating values of strain energy and dividing it by the period to failure. The availability of the new factor was approved by additional ozone tests with different ozone concentrations, temperatures and loading conditions. Keywords '. Ozone, strain energy crack, visco-elastic, creep, relaxation
社団法人日本建築学会の論文
1990-11-30