Liquid oxygen compatible epoxy resin: modification and characterization
The bisphenol A epoxy resin was modified by the polycondensation between tetrabromobisphenol A and bisphenol A epoxy resin. After curing using 4,4′-diaminodiphenyl methane (DDM) and 4,4′-diaminodiphenyl sulfone (DDS), the liquid oxygen compatibility of bisphenol A epoxy resin and modified bisphenol A epoxy resin was measured by the mechanical impact test (ASTM D2512-95). The results suggested that the modified bisphenol A epoxy resin curing using 4,4′-diamino diphenylmethane (DDM) was compatible with liquid oxygen. The thermogravimetric analysis (TGA) revealed that the modified bisphenol A epoxy resin has lower temperatures of the initial degradation and the maximum mass loss rate compared with unmodified. The X-ray photoelectron spectroscopy (XPS) measurement results indicated that the C–C/H groups were oxidized to C–O–C/H and/or CO groups during the impact process. The mechanical properties of all samples were measured at room temperature (RT) and nitrogen temperature (77 K). The flame-retardant modification of epoxy resin may be an effective way to obtain the compatible epoxy resin material with liquid oxygen.