| The thiol curing agent can rapidly cure the epoxy resin at room temperature under the catalysis of a tertiary amine,which is very convenient to use.At present,domestic production of polythiol is still very small,mostly relying on imports,and the cured products have the disadvantages of poor heat resistance and low bonding strength.In this paper,the polythiol curing agent was modified by molecular structure design,and the curing behavior of the modified product was studied.Firstly,tetrakis?3-mercaptopropionic acid?pentaerythritol ester was modified with toluene diisocyanate as a modifier to synthesize a modified polythiol curing agent A.The smooth progress of the reaction was verified by infrared and nuclear magnetic characterization.A high performance room temperature fast curing epoxy resin cured product was prepared by using 2,4,6-tris?dimethylaminomethyl?phenol?DMP-30?as a promoter and A as a curing agent and epoxy resin E51.Tests on gel time,tensile shear strength,heat resistance and water resistance of the cured product showed that when the ratio of epoxy resin to curing agent A was 1:1 and the amount of accelerator DMP-30 was 3%,The curing system has a tensile shear strength of 31MPa and a Vicat softening point of 76.7°C in 5 min.The Shore hardness decreased by 33.7%after 240 h of water treatment,compared with the bonding strength and heat resistance before modification.Water resistance is significantly improved.A modified polythiol curing agent B was synthesized by using isobornyl methacrylate as a modifier.The smooth progress of the reaction was verified by infrared and nuclear magnetic characterization.A high-performance room temperature fast curing epoxy resin cured product was prepared by using DMP-30 as a promoter and B as a curing agent and E51.Tests on gel time,tensile shear strength,heat resistance and water resistance of the cured product showed that when the ratio of epoxy resin to curing agent B was 0.8:1,the amount of accelerator DMP-30 was 7When the curing system is at 9 min,the tensile shear strength is 28.6 MPa,the Vicat softening point is 75.8°C,and the Shore hardness is decreased by 37.2%after 240 h of water treatment,compared with the bonding strength and resistance before modification.Heat and water resistance are significantly improved.A modified polythiol curing agent C was synthesized by using o-tolyl glycidyl ether as a modifier.The smooth progress of the reaction was verified by infrared and nuclear magnetic characterization.A high performance room temperature fast curing epoxy resin cured product was prepared by using DMP-30 as a promoter and C as a curing agent and E51.Tests on gel time,tensile shear strength,heat resistance,water resistance,and curing reaction process and reaction kinetics of the cured product showed that when the ratio of epoxy resin to curing agent C was 0.8:1,the accelerator When the addition amount of DMP-30 is 5%,the solidification system gels at 5 min,the tensile shear strength reaches 32 MPa,the Vicat softening point is 80°C,and the Shore hardness decreases by 32.1%after 240 h of water treatment.Before the bond strength,heat resistance and water resistance are significantly improved.The curing reaction reacted rapidly in the first 10 minutes,slowed down in 10-25 minutes,and entered the post-cure process after about 50 minutes.The curing reaction kinetics model??t?=1-[1-4.61×104exp?-66350.40/T?×t]20.24 was obtained by non-isothermal DSC method.The optimum curing temperature was 305.25K. |
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