LAYERED SILICATE/ORGANIC POLYMER NANOCOMPOSITE MATERIALS FOR ROCKET COMPONENTS

Materials intended for rocket motor casing must offer excellent thermal stability, good mechanical properties, high char yields, superior ablation resistance during operation to eliminate case rupture. Out standing bonding of the propellant to the casing and/or insulating interphase to eliminate bondline failure, and low cost processing so that the process is competitive with current methodologies. We propose to use a layered silicate/organic polymer nanocomposites (LSPN) hybird as a complimentary alternative to the liquid crystalline polymer routes currently being developed by the Air Force. Exfoliated layered silicates will be combined with novel aminofunctional silsesquioxanes and organic epoxy resins to form thermoset networks. These hybird thermosets will offer the thermal stability, mechanical properties, char yields, and ablation resistance needed for the harsh rocket casting requirements. In Phase I, the objectives are to (1) optimize exfoliation processes, (2) establish guidelines for optimizing performances through formulation of various blends and curing studies. Materials involved include exfoliated hectorite and motmorillonite, (NH2(CH2)3SiO1.5)8] cube, DGEBA resins (DER 331 and 667), aromatic (DDA) and a liphatic (ethylenediamine, hexylenediamine) amine curing agents. Impact tests will be used as the first screening mechanism. Blends with superior impact strength will then be subjected to subsequent tensile and charring tests. Ablation resistance will be studied only for the best candidates that complete the selection process. Once ideal systems are determined, 2x4 casings will be built for the pressurization tests. Further refinement of the selected systems is to be conducted in Phase II.