Development of polyimide materials for use in solar energy systems. Semi-annual technical progress report, August 1, 1978-January 31, 1979

Abstract

This report covers six months of effort on a program to optimize and characterize improved insulation materials for solar energy systems. Two separate and distinct products have been studied, a lightweight flexible insulating foam and a high density, rigid, load bearing insulating foam. These products are derived from a polyimide resin, the formulations and processes for which were developed under NASA-JSC sponsored programs. These materials are non-burning and do not emit measurable quantities of smoke or toxic byproducts. Candidate resins were selected on the basis of cost, expected foam insulating and weatherability properties and ease of production. A critical characterization criteria was established in the form of environmental exposure resistance. The foams were evaluated on the basis of this direct exposure test. Studies initiated to improve the resistance included additive studies, using reinforcements and uv absorbers, and postcure studies. The various formulations were also screened on the basis of humidity resistance. On the basis of testing conducted, four different resin formulations at a foam density of approximately 16 kg/m/sup 3/ (1.0 PCF) are meeting minimum requirements. Candidate selection is still in progress. The rigid foam was optimized through a glass reinforcement study and a process parameter study. This work wasmore » characterized on the basis of low cost, ease of production, and the critical property requirement of compressive strength. The result of these studies was an optimized glass strand/microballoon reinforced foam which meets the tested property goals at a density of approximately 240 kg/m/sup 3/ (15.0 PCF). This candidate material is under advanced testing.« less