THE EFFECT OF EPOXY RESIN AND CURING AGENT STRUCTURE ON ABLATIVE PROPERTIES.

The reported is the second phase of a correlation of the chemical and physical properties of a polymer with its ablative properties (See AD-467 049 for phase I). Epoxide resins and curing agents were employed as model systems. Thermogravimetric analysis, cross-link density studies, infrared spectroscopy and 'alpha-rod' testing in the oxyacetylene burner facility were employed in the evaluation of the various systems. Amine cured epoxide structures produced high char rates (7.1 to 21.0 mils/sec) and low times to 200C (33 to 47 sec). Certain anhydride cured epoxides, namely methyl bicyclo (2.2.1) heptene-2,3-dicarboxylic anhydride (NMA) and 3,3',4,4'-benzophenone tetracarboxylic dianhydride (BTCD) were found to give good performance with low char rates (2.2 to 5.0 mils/sec) and high times to 200C (91 to 101 sec). Epoxides with a polyphenyl backbone gave the best overall performance, although resorcinol diglycidyl ether performed well also. Resin purity was found to be fairly critical in regard to ablative performance. (Author)