| Epoxy resins are widely used.However,the unmodified epoxy resin has insufficient bonding performance and poor toughness.At present,the most popular method to improve the toughness of epoxy resin is to introduce a flexible skeleton structure through chemical modification.In this paper,cardanol glycidyl ether(CGE)and polyepoxy cardanol glycidyl ether(PECGE)were used to modify the epoxy resin respectively.The purpose was to improve the toughness and bonding performance of epoxy resin cured products,by introducing the long unsaturated fatty acid side chain of cardanol into the epoxy resin structure.The properties of four kinds of amine epoxy curing agents(triethylenetetramine(TETA),low molecular weight polyamide 300#,polyetheramine D230 and isophorone diamine(IPDA)-modified epoxy resin systems were studied.The main content of research included the curing reaction of modified resin at room temperature and heating conditions by differential Scanning calorimeter(DSC)and Fourier Transform Infrared Spectrometer(FT-IR),the thermal stability of the cured product by thermogravimetric analysis(TGA),and the room temperature and 80℃tensile shear strength and room temperature peel strength of the cured productFirst,CGE was used to modify the epoxy E-51 system.The introduction of CGE increases the pot life of epoxy adhesives,and in most cases improves the degree of room temperature curing reaction and the bonding performance.When the CGE content is 10% and 300# curing agent is used,the room temperature curing 3d curing degree is increased by 14.9%,and the corresponding room temperature and 80 ℃ shear strength are increased by 31.7% and 13.2% respectively;when using D230 curing agent,the room temperature curing 3d curing degree increased by 32.2%;when using isophorone diamine curing agent,curing at room temperature 3d curing degree increased by 2.2%,90°C curing 2h peel strength was 2.49N/mm,increased by 106%.When using 300# curing agent,the shear strength at room temperature and 80℃ was increased by 31.7% and 13.2% respectively.As the amount of CGE increases,the modified resin’s TG thermal performance decreases.In this paper,meta-chloroperoxybenzoic acid(MCPBA)is used to oxidize the unsaturated bonds on the long fat chain in the CGE structure to synthesize polyepoxy cardanol glycidyl ether(PECGE).Compared with unmodified E-51 resin,the room temperature shear strength of 10% PECGE modified epoxy resin-TETA system is increased by 88.3%;when using 300# curing agent,the room temperature and 80℃ shear strength are increased by 20.4% respectively 14.5%;when using D230 curing agent,the room temperature shear strength increased by 20.5%;when using TETA curing agent,30% PECGE modified epoxy resin was cured at 90℃ for 2h,the peel strength was 2.51N/mm,which was improved 107%.Compared with the CGE modified E-51 system,the three curing agents(TETA,300#,D230)-PECGE modified epoxy resin system showed higher TG thermal stability.In the TETA curing agent-resin system,the PECGE modified epoxy resin has a higher degree of room temperature curing reaction and higher heat curing adhesion performance.Among them,the peel strength of the 10% PECGE modified epoxy adhesive is higher than that of CGE modified epoxy increased by 53.8%. |
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