Enhancing liquid‐oxygen compatibility of epoxy resins by direct physical blending of metal organic framework

Abstract Based on the advantages that polymer materials have shown in the aerospace industry, they can also be used as liquid oxygen (LOX) tanks to reduce weight. However, pure epoxy resin (EP) needs to be modified due to its incompatibility with LOX. In this study, metal–organic frameworks (Cu‐BDC) were prepared in one step by solvothermal reaction and physically mixed directly into the resin to form a composite. The LOX mechanical impact tests showed an impact response sensitivity of 0 and the composite was compatible with LOX at an addition level of 3 wt. %. The mechanism of LOX compatibility of EP/Cu‐BDC composites was analyzed by a series of characterization means, and it obtains EP composites with higher quality char layers resulting in a more efficient barrier effect. The rheological properties of the liquid‐oxygen compatible EP composites were analyzed, and the gel temperature (T gel ) and gel time (t gel ) were 127.85°C and 65.4 min, respectively, with a good processing window. The mechanical properties of EP and EP/Cu‐MOF were also analyzed at room temperature (RT) and 90 K. The bending strengths at 90 K were 268.98 MPa for pure EP and 327.29 MPa for EP/Cu‐BDC 3%. Meanwhile, the low‐temperature impact strengths of pure EP and EP/Cu‐BDC 3% were 10.31 and 19.10 kJ/m 2 , respectively. At low temperatures, the bending and impact strengths of EP/Cu‐BDC 3% increased by 21.68% and 85.26%, respectively, compared to pure EP. Highlights Direct physical addition of MOF makes EP compatible with liquid oxygen. Low physical addition of MOF (3 wt. %). EP/MOF composites have good rheological properties. EP/MOF has superior flexural and impact resistance to pure EP. Analyze the liquid oxygen compatibility mechanism.