| As a structural adhesive,epoxy resin has some defect such as high brittleness and insufficient temperature resistance.For example,in order to improve the toughness of epoxy,the liquid rubber,acrylic shell core particles,polyurethane and other toughening agents are often added,but it will bring adverse effects on the heat resistance of epoxy resin.The modification of epoxy resin with inorganic nanoparticles is expected to balance the toughness and heat resistance.At present,the research on inorganic and organic hybrid epoxy resin is the hot spot of epoxy resin modification.In this study,SiO2 hybrid epoxy resin is synthesized by sol-gel method,and the structure,curing reaction,bonding performance,heat resistance,microstructure of fracture surface of cured epoxy resin are studied.Firstly,flexible polyetheramine D230 is used as curing agent to investigate the effect of different SiO2 contents on the properties of hybrid epoxy resin.The results show that the bonding strength and heat resistance of epoxy resin increase and then decrease with the increase of SiO2 content.When the SiO2 content is 1%,the bonding strength and heat resistance are the best.The shear strength at room temperature,80?and 120?is 40.02MPa,30.21 MPa and 9.64 MPa,respectively.Compared with that of E-51/D230,the peel strength increases by 15%,the Tg increases by 4.14?,the temperature of 5%thermal weight loss increases by 10?,and the weight loss rate decreases by 6%at 400?.The heat-resistant m-xylylenediamine is used as curing agent,the glass transition temperature of 1%SiO2 hybrid E-51/MXDA increases by 5?,the shear strength at room temperature,80?and 120?increases by 21%,20%and 39%,respectively,the temperature of 5%thermal weight loss increases by 5?,and the weight loss rate at 400?decreases by 5%.The shear strength at high temperature and TG performance of m-xylylenediamine curing agent system are lower than polyetheramine D230 cured agent system.The 300#polyamide and TETA are used as room temperature curing agents,the shear strength of room temperature curing SiO2 hybrid E-51/300#at room temperature,80?and 120?are increased by 31%,66%and 39%than that of un-hybrid epoxy,respectively.The shear strength of room temperature curing SiO2 hybrid E-51/TETA at room temperature and 120?are increased by 48%and 67%than that of un-hybrid epoxy,respectively,and the shear strength changes little at 80?.The temperature of 5%thermal weight loss of SiO2 hybrid E-51/300#is slightly increases by 0.6?compared with that of un-hybrid E-51/300#,and the weight loss rate at 400?reduces by 4%.The temperature of 5%thermal weight loss of SiO2 hybrid E-51/TETA is increases by 0.6?compared with that of un-hybrid E-51/TETA,and the weight loss rate at 400?decreases by 2%.Compared with the two heating curing agent systems mentioned above,the performance of 5%TG of the two curing agent systems at room temperature is lower.The curing reactions of SiO2 hybrid epoxy resin cured with four kinds of amine curing agent are investigated by IR analysis,and it proved that the epoxy organic crosslinking reaction,SiO2 inorganic crosslinking reaction and epoxy-SiO2 organic and inorganic graft crosslinking reaction occur in the curing process.The SEM is used to investigate the microstructure of SiO2 hybrid epoxy resin cured with the above four kinds of amine curing agent.SiO2 condensation or precipitation is not found,which proves that the silica inorganic network is evenly dispersed in the epoxy organic network.The DSC is used to investigate the curing reactivity of SiO2 hybrid epoxy resin cured with the above four kinds of amine curing agent.Compared with the pure epoxy resin system,the initial curing temperature and peak curing temperature of SiO2 hybrid epoxy resin reduce,which indicates that the introduction of SiO2 inorganic network improves the reactivity of amine-cured epoxy resin. |
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