Development and evaluation of elastomeric materials for geothermal applications. Annual report, October 1977-December 1978

The research involved formulation of commercially available materials and synthesis of new elastomers. Formulation studies at JPL and elsewhere produced a material having about 250-350 psi tensile strength and 30 to 80% elongation at 260/sup 0/C for at least 24 hours in simulated brine. The relationship between these laboratory test results and sealing performance in actual or simulated test conditions is not entirely clear; however, it is believed that no conventional formation or casing packer design is likely to perform well using these materials. The synthetic effort focused on high temperature block copolymers and development of curable polystyrene. Procedures were worked out for synthesizing these new materials. Initial results with heat-cured unfilled polystyrene gum at 260/sup 0/C indicated a tensile strength of about 50 psi. Cast films of the first sample of polyphenyl quinoxaline-polystyrene block copolymer, which has a graft-block structure consisting of a polystyrene chain with pendant polyphenyl quinoxaline groups, showed elastomeric behavior in the required temperature range. Its tensile strength and elongation at 260/sup 0/C were 220 to 350 psi and 18 to 36%, respectively. All of these materials also showed satisfactory hydrolytic stability. A procedure for the synthesis of a linear block copolymer of this type hasmore » been devised, and the required new intermediates have been synthesized and characterized. A description of the previous year's work is included in an appendix.« less