| Epoxy adhesives have excellent adhesion and corrosion resistance. And its room temperature curing properties make it easy to use. Therefore, the epoxy adhesives have occupied the main position in adhesives and have the name of "universal adhesives". With the continuous progress of science and technology, the common used room temperature curing epoxy adhesives become taking on its many disadvantages especially poor heat resistance. It is now losing the large adhesive market that used to belong to it, such as military, areospace, traffic, energy, construction and so on.This research made use of the typical Mannich-based synthesis with the tested-best monomer to prepare the room temperature curing epoxy curing agent with heat resistance. A variety of excellent new systems of room temperature curing epoxy adhesives with good heat-resistance was found out through the common filler, the common epoxy matrix(EP), self-made EP mixture and other factors.The final optimal dispersion process that nano-titanium dioxide dispersed into the epoxy matrix was obtained by a variety of methods. The impact of nano-titanium dioxide to the best epoxy adhesive systems through the optimal dispersion process method was found out. The anti-media performance of the epoxy adhesives made with the optimal system was found out through the durability testing of curing adhesive material and the corrosion resistance testing of the adhesive bonding pieces against a variety of media.(1) The monomer of mannich base of the optimal synthesis was selected through searching literature and preliminary testing, that is paraformaldehyde, m-cresol and hexamethylenediamine. The optimal synthesis process was obtained by the exploration of the synthesis process of Mannich base curing agent, that is, the reaction temperature and time is 100℃ and 2.5h respectively, the mole ratio of m-cresol, paraformaldehyde and hexamethylenediamine is 1:1:1.3 and the stirring speed is 200 r/min. The self-made curing agents have better performance compared with the commercially available ones.(2) The best room temperature curing epoxy adhesive was found out through single factor experiments and the orthogonal experiments, that is, GW-18:(E-44) 10g, (20# curing agent) 4g, (boron carbide) 14g, (KH-560) 0.5g. Its shear strength is 20.90MPa at the room temperature,27.48MPa at 150℃ and 24.82MPa at 200℃.(3) The optimal dispersion process that the nano-titanium dioxide (nano-TiO2) dispersed into EP was obtained by a variety of methods, that is, first to decorate the nano-titanium dioxide using sodium dodecylsulfate (SDS) with the mass ratio of SDS:nano-TiO2 is 1:1, and then add 0.6g per lOg EP of the coated nanoparticles into EP when the temperature of it is 50℃ and with mechanical stirring at 200r/min for 20min. Finally mixes them for 60min under 90w ultrasound power,50℃ and 28Hz in the closed system. The performance of the best adhesive was enhanced by dispersing nano-TiO2 into EP under the optimal dispersion process, but little change come out with some enhancement.(4) The anti-media performance of the optimal epoxy adhesives was found out through the durability testing of curing adhesive material and the corrosion resistance testing of adhesive bonding pieces against a variety of media. The results have shown that the optimal epoxy adhesive has a good resistance in gasoline, kerosene, water, sea water, alcohol, tap-water and so on, but has a bad resistance in the concentrated acid, formaide, vinyl acetate and tetrahydrofuran. |
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