Study On The Synthesis Of Schiff Base Metal Complexes And The Kinetics Of Curing Epoxy

Organic metal complex curing agent is a kind of high performance latent curing agent,with good mechanical properties and heat resistance for its curing product.In this work,a series of Schiff base metal complexes were synthesized,and a detailed study on its synthesis and curing characterization of the Schiff base metal complexes/epoxy system,including:(1)Salicylaldehyde,fatty amines,metal acetate were used for the preparation of Schiff base metal complexes.Through the comparison of different synthesis methods, we determined the best synthesis process for each product.The product were characterized by IR,NMR,elemental analysis,single crystal diffraction,the result show that the products were consistent with the goal products.Then the melting point and purity of the products were measured.(2)The Ni(sal)₂trien/epoxy and Ni(sal)₂dien/epoxy system were analyzed by DSC at a variety heating retes,from the results we infer that the first pesk corresponding to the amine-epoxy reaction,the second for the hydroxyl-epoxy reaction.(3)Through the UV spectra,infrared spectra,DSC of different amount of curing agent epoxy system,we confirmed the above-mentioned mechanism.Then the curing mechanism of the Schiff base metal complexes/epoxy system was suggested by the follow:first,the coordination bond of the secondary amine with metal ion is broken under heating condition;the secondary amine of the Schiff base metal complexes is react with the epoxy group;after a period of time,the amount of secondary amine hydrogen decreases,but the amount of hydroxyl increase significantly,so the hydroxy-epoxy reaction is dominant in the later stage.(4)The theoretical analysis shows that,ideal latent curing agent have reaction kinetics characteristics of higher curing reaction activation energy and higher apparent frequency factor;or the curing reaction activation energy increases significantly with the decreasing temperature.(5)One-component epoxy resin system was prepared of Schiff base metal complexes with epoxy.resin system were determined by different kinetic parameters of curing reaction.The apparent activation energy Eαand pre-exponential factor A of the different curing reaction system were determined.The Eαand A for different amount of curing agent was also studied,the result show that the reduce of curing agent will make the Eαand A,but had no effect on the reaction order n.