Research On Cryogenic Mechanical Properties Of Modified Epoxy Resins

Epoxy resins have tremendous potential in the applications of cryogenic engineering projects, such as spacecraft, superconducting cable technologies and etc,because of excellent mechanical properties,electric insulation and chemical resistant properties. However, the poor toughness and shock resistance of epoxy resins at cryogenic temperature limit its applications in cryogenic engineering projects. To solve this problem, the cryogenic mechanical properties of epoxy resins modified by different kinds of modifiers were investigated.The modified epoxy resins were synthesized through epoxy resin and polyether sulfone, polyurethane, polyether polyol,silane coupling agent, hydroxyl silicone oil and ethyl acrylate,respectively. The tensile and bending strengths at cryogenic temperature were also investigated in this paper. Combined with FTIR and SEM, the microstructure and toughening mechanism of modified epoxy resins were analyzed.The results revealed that at-50℃ the tensile and bending strengths at cryogenic temperature increased, and then decreased, with the increasing of polyether sulfone, polyurethane, polyether polyol,silane coupling agent and ethyl acrylate. However, the cryogenic tensile and bending strengths of epoxy resins modified by hydroxyl silicone oil increased, and then kept slightly change, when the dosage of modifier increased. When the contents of polyether sulfone,polyether polyol, silane coupling agent, hydroxyl silicone oil and ethyl acrylate were 40wt%, 20wt%, 20wt%, 3wt% and 15wt%,respectively, the tensile strengths of modified epoxy resins increased by 43.3%, 43.4%, 47.6%, 17.7% and19.6%, and the bending strengths increased by 91.4%, 105.3%, 39.5%, 37.0% and 21.8%. Owe to the formation of interpenetrating polymer network between epoxy resin and modifiers, the tensile and bending strengths of modified epoxy resin containing 20wt% of polyurethane were the largest, which were120.38 Mpa and 227.23 Mpa, and increased by 50.8% and 124.5%,respectively. The mode of fracture changed from fragile to ductile for the epoxy resin enhanced by polyurethane, and phase separation did not occur at cryogenic temperature.