DELAYED ACTION, FOAM-IN-PLACE POLYURETHANE FOR USE IN AN AEROSPACE ENVIRONMENT
Final rept., Feb 1961-Jan 1962
HUGHES AIRCRAFT CO CULVER CITY CA
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Materials and techniques were developed to meet the requirement of a delayed action, foam-in place polyurethane for use in an aerospace environment. The methods investigated for preparation of the special polyurethane included a number of chemical blocking reactions, molecular sieves and encapsulation techniques, all designed as restraining agents to inhibit the activity of the isocyanate component. The successful method finally developed utilized the principle of solid components to assure low reactivity and good storability. The optimum compound employed a sterically hindered solid diisocyanate, dianisidine diisocyanate, a solid diol, an ethylene oxide adduct of bisphenol A, a solid triol cross linker, trimethylol propane, and a solid catalyst, dibutyl tin di-2- ethyl hexoates. The resulting powder mixture was found to have storage stability of at least two months when stored at room temperature. Structural components, made to demonstrate the utility of the powder, consisted of a seven-foot diameter balloon, which using pre-distributed powder on its surface, was inflated and rigidized at a simulated altitude of 150,000 feet.