Polymer systems in geothermal applications

The feasibility of using a copolymer composed of styrene, acrylonitrile, and acrylamide or methacrylamide in the formation of a high-strength thermally and chemically stable polymer concrete for use in geothermal environments has been demonstrated. Specimens produced with the copolymer in conjunction with an aggregate containing sand and portland cement had compressive strengths in the range of 25,000 to 30,000 psi at 20°C and were thermally stable up to ∼240°C. A study of the effect of monomer concentration on the properties of the polymer concrete indicated that the optimum concentration is in the range of 12 to 13 wt. %. Increased monomer concentrations lead to a nonuniform polymer distribution within the composite, resulting in a deterioration of the properties. The optimum properties are obtained when the monomer is used in conjunction with an aggregate containing 70 to 80 wt. % silica sand and 20 to 30 wt. % portland cement. The results from laboratory and field evaluations in progress indicate that the materials can be used for pipe or as protective liners on pipe and vessels in electric generating and direct utilization geothermal processes.