Minjing Liu

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.

Effect of hexabromocyclododecane and antimony trioxide on flame retardancy of bisphenol A epoxy resin

Abstract In the present work, the hexabromocyclododecane and the antimony trioxide were introduced into the bisphenol A epoxy resin to improve its flame retardancy. The effects of hexabromocyclododecane and antimony trioxide on flame retardancy of bisphenol A epoxy resin were estimated according to ASTM D2512-95 (2008). The specimen cured by T-31, with the addition of hexabromocyclododecane, did not show any flash and explosion during the 20 times of mechanical impact, whereas slightly empyreumatic scent was detected. The explosion was observed for the other specimens. The resin particles on the surface of the specimen after the mechanical impact were more than that before the mechanical impact, which was attributed presumably to the mechanical impact at the low temperature resulted in the crushing of the resin materials. It also indicated that bisphenol A epoxy resin cured by 593 with antimony trioxide at the low temperature had low flexibility. The XPS analysis confirmed that the surface of the specimen observed explosion was readily reacted with liquid oxygen. The O/C ratios of the specimen cured by T-31, with the addition of hexabromocyclododecane, before and after the mechanical impact were statistically approximate to 0.223 and 0.238, respectively, which revealed that the specimen was compatible with liquid oxygen.

Synthesis and characterization of a liquid oxygen-compatible epoxy resin

The bromine element was introduced into an epoxy resin to improve the liquid oxygen compatibility of the epoxy resin. After curing using 4,4′-diamino diphenylmethane, the liquid oxygen compatibility of all specimens was measured by the liquid oxygen mechanical impact test (ASTM D2512-95). The results suggested that the bromine-modified epoxy resin (BEP) was compatible with liquid oxygen, whereas the bisphenol F epoxy resin (EP) had poor liquid oxygen compatibility. The results of thermogravimetric analysis indicated that the incorporation of tetrabromobisphenol A into EP could accelerate the second-stage thermal degradation of BEP, leading to improvement of the liquid oxygen compatibility. X-ray photoelectron spectroscopy analysis indicated that the C–C/H groups on the surface of specimens could be oxidized to C–O–H/C and C=O groups during the impact process. The mechanism of bromine enhancement on the liquid oxygen compatibility of epoxy resin is proposed.