Study On The Polymer's Compatibility With Liquid Oxygen

The purpose of the paper is to study the mechanism of polymer's compatibility with liquid oxygen (LOX), so as to provide theoretic instructions for the study of LOX compatible polymer and to expand the application of polymer.Epoxy resins and cyanate esters co-curing system were selected as the material systems. The research involves polymer's static compatibility with LOX, factors affecting the impact sensitivity of polymer in LOX, the essence of LOX compatibility, the process of impact sensitivity of polymer in LOX, the study of polymer's modification to improve the compatibility, and the polymer's anti-cryogenic property.The study of polymer's static compatibility with LOX showed that polymer can co-exist with LOX safely, and the non-compatibility appears only when outer energy was introduced.The study of the physical and chemical factors affecting the impact sensitivity of polymer in LOX showed that small entrapped bubbles, enhanced fibers can improve the sensitivity, while proper identity surface coarseness of the polymer and the higher adhesive intensity between matrix and fibers can decrease the sensitivity. With the increase of thermolysis temperature, anti-oxidation, flame retarded properties, and the flash point of polymer, the impact sensitivity decreases. The heat of combustion and the oxygen index of polymer characterize the LOX compatibility in the ability of sustained burning, having no direct relation with the impact sensitivity.The essence of the LOX compatibility of polymer was approached which indicated that the non-compatibility is an oxidation-combustion reaction. The assumed process of the impact sensitivity in LOX involves five steps including energy introduced by impact.Guided by these, two kinds of modified epoxy systems basically compatible with LOX were found by increasing their anti-oxidation and flame retarded properties.Besides, the anti-cryogenic properties of epoxy and cyanate system were studied. The results showed that the materials can withstand the -196~30℃ cycling without any flaws and cracks, and the tensile strength varies ±10% after marinated in liquid nitrogen for 50 hours.