Water swellable rubber composition having stable swelling property at high temperatures

Abstract

A water swellable rubber composition comprising (a) a non-water swellable base rubber, (b) an ethylene oxide based hydrophilic elastomer having from zero up to 20 mole % of a crosslinkable curable functional group, and (c) a water swellable non-elastomeric material. The composition has excellent water swell characteristics under prolonged exposure to high temperature and various electrolyte solutions and is suitable for oil field applications. When (b) has from zero to less than 5 mole % of crosslinkable functional group, the amount of (b) is between about 30 parts and 300 parts by weight based on 100 parts by weight of (a) and the amount of (c) is between about 20 parts and 200 parts by weight based on 100 parts by weight of (a), the composition is characterized by good shape retention after undergoing constrained swell, and a high degree of constrained swell at elevated temperatures in different saline concentrations.

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