Studying On Synthesis And Properties Of New Epoxy Resin Curing Agent

Epoxy Resin are widely used in aerospace, shipping, civil engineering, machinery manufacturing and other fields because of its strong bonding strength, solvent resistance, excellent electrical performance, good mechanical properties, and other good features. However, epoxy resin used alone almost has no value, but if used with curing agent to generate a three-dimensional network of insoluble and unmolten product, it can play the best performance. Aromatic Diamines account for a large proportion in the epoxy resin curing agent, and they endow epoxy resin with good heat resistance, solvent resistance and mechanical strength, however, traditional diamines are toxic, easy to evaporated and are hard to form a homogeneous system with epoxy resin at room temperature, thus, the modification of DA is a hot research.Therefore, in this article, a novel epoxy resin curing agent was synthesized with the introduction of BMI structure into the traditional diamine curing agent, since the distance of the amino groups are increased because of the BMI structure, the crosslinking density of the epoxy resin curing systems decreases, so the toughness of the epoxy resin are strengthened. The main research is as follows:A new epoxy curing agent was synthesized, and the structure of the productions were proved by FT-IR and NMR tests. PBMI-DDE with good comprehensive properties was selected, then the curing kinetics of E-51/PBMI-DDE/DDE curing systems were explored by Differential scanning calorimetry (DSC), morever, the curing kinetic parametres were calculated, and the proper curing process was determined.Finally, the thermal properties of the curing systems was discussed by TGA and DMA tests, and the influences of E-51/PBMI-DDE/DDE ccuring systems with different content of PBMI-DDE were also studied by the impact test, bending test and water absorption test. The results showed that the, the glass transition temperature of the cured productions decreased with the increasing content of PBMI-DDE. The flexural modulus increased with the increasing content of PBMI-DDE, this was because of the introduction of a large number of rigid maleimide ring structures into the system, and layed an portant role in strengthening and toughening modification of epoxy resin. The TGA test showed that the initial decomposition temperature, T5%, and the residual carbon content rate of the curing system increased with increasing of PBMI-DDE, and this was mainly due to a large number of rigid maleimide ring structures in the cured products. The impact strength and flexural strength improved first with the increasing content of PBMI-DDE and then decreased, this was because PBMI-DDE could decrease the crosslinking density of the curing systems which could improve the toughness of the productions, while in the late stage, the crosslink density of the systems was so low that it made the distance to long between crosslinking points, therefore it weaken the strength of the material. Water absorption test showed that at low temperature, the water absorption of the curing productions were mainly influenced by the concentration of polar group, so it decreased with the increasing of PBMI-DDE, however when at high temperature, the free volume was the dominant factor, the higher the temperature, the stronger the collision of water molecules, thus the diffusion and penetration of water could be more easier, so the water absorption of curing productions increased while the content of PBMI-DDE increased.