Effect of Liquids on Rubber and Its Measures

When a rubber sample is in contact with a liquid, a complex interaction between these two materials may take place. The action of the liquid on rubber results in absorption of the liquid by the rubber, sometimes followed by extraction of soluble constituents from the rubber. As usual, absorption is greater than extraction, so an increase in volume (or weight) results. It should be said that a decrease in volume or in weight of the rubber under these conditions implies more serious damage to the rubber than when swelling is observed. 

Tests in which rubber samples are exposed to liquids are called swelling tests because of the resulting change in volume of the test pieces. The liquids generally used are aromatic compounds, the most common being toluene, as it is less volatile than benzene. These tests are also called oil ageing when standard grades of mineral oil are the liquids [1]. 

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