Synthesis and Ballistic Evaluation of Selected Transparent Polyurethane Block Copolymers, Part II. Further Changes in Formulation

In an extension of previous work on polyurethane block copolymers for transparent armor applications, several additional variations of the basic 2,4- toluene diisocyanate/polytetramethylene oxide/1,4-butanediol formulation have been investigated. It has been found that excess diisocyanate in a given formulation improves ballistic resistance and that decreasing the amount of polyether (soft segment) has the same effect. More generally, it has been found that increased sample hardness (Shore D) parallels improved ballistic performance. High-speed photographic data have shown that these materials continue to absorb large amounts of ballistic energy, with relatively little of this energy manifested as fragment kinetic energy. A technique for the preparation of void-free ballistic test specimens involving the use of a polytetrafluoroethylene mold is also described. See also report dated Dec 73, AD-773 689.