Preparation of temperature resistant epoxy resin with rapid curing at room temperature and properties of modified sealant
Phthalic acid diglycidyl ester(PADE)was synthesized by using phthalic anhydride and epichlorohydrin as raw materials,and then it was used as matrix resin to prepare two-component sealant.The structure of PADE and the surface drying time,hardness,mechanical properties,thermal properties,thermal stability,and microstructure of two-component sealant were measured or characterized.The research results showed that,(1)The product was structurally characterized by FT-IR and 1H-NMR.The epoxy value of the product was 0.58 mol/100 g,and the viscosity at room temperature(25℃)was 2 245 mPa·s.(2)The surface drying time of PADE-10%sealant was shortened by 30 minutes compared to the sealant without PADE added.(3)As the amount of PADE added increased,the tensile strength,elongation at break,flexural strength and impact strength of epoxy sealant first increased and then decreased.When the amount of PADE added was 10%,the comprehensive mechanical properties were excellent.The tensile shear strength of PADE-10%sealant at different aging time was higher than that of PADE-0 sealant,indicating that this adhesive had certain aging resistance.(4)It was found that PADE had a catalytic effect,reducing the activation energy and increasing the reaction speed.With the addition of PADE,the Tg of the system continued to decrease,from 93.1℃ to 81.6℃.(5)The T10%and Tmax of PADE-0(pure E-51)sealant were lower than those of PADE-10%sealant,indicating that the addition of PADE formed a highly crosslinked network,making the cured product structure denser.Adding an appropriate amount of PADE could improve the heat resistance of the sealant and made the sealant have better mechanical properties.(6)By studying the effect of adding PADE on the bonding mechanism of modified E-51 epoxy sealant,it was found that the fracture surface of E-51 cured product exhibited brittle fracture characteristics,while the epoxy sealant added with 10%PADE showed an ordered band structure on the fracture surface,accompanied by a large number of small silver lines,exhibiting ductile fracture characteristics,indicating that PADE had the enhancing and toughening effect.
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