The Influence Of Kinds And Equivalent Ratio Of Amine Curing Agent On Crosslinking Network And Composite Material Performance

As people's requirements to the materials properties is higher and higher, epoxy resin and carbon fiber composite material has been rapid development. In the process of preparation of carbon fiber composite materials production, modulus of resin matrix has an important influence on the performance of the final composite materials. The amount of amine curing agent in the carbon fiber reinforced resin composite accounted for more than half of total curing agent.What's more, amine curing agent structure is varied, The performance of the cured compound is different. So a reasonable choice for the kinds of curing agent and usage amount are a very meaningful thing. Fully understanding the influence of the kind and flexibility of the amine curing agent for epoxy resin cured compound and carbon fiber composite is our primary task of this topic research. This topic main work is as follows:(1) We research the influence of stoichiometric ratios of curing agent/epoxy resin crosslinking network structure of the cured epoxy resin and the influence of mechanical properties. In order to understand comprehensively the flexible curing agent (D230) and rigid curing agent (DDM) were selected, curing agent of epoxy resin with stoichiometric ratios range from 0.8 to 1.6. Tests shows in equivalence ratio, crosslinking network of cured compound is the most complete, and Tg is the highest, but the mechanical properties is worst.In the epoxy-rich system or amine-rich system, the cured compound's crosslinking network is incomplete, but that can get better mechanical properties, especially the modulus, variation trend along with the change of stoichiometric ratios is most obvious. Through the free volume size test, we established dangling clain model of the influence of the stoichiometric ratios on cured compound performance.(2) We research the influence flexibility of different three amine curing agent on two kinds of carbon fiber composite materials. In the experiment, three kinds of different flexibility curing agent were selected, D230, DMDC and DDM respectively, the structure of three kinds of curing agent, polyether amine type, alicyclic amine respectively and aromatic amine curing agent. Besides high modulus carbon fiber M40 carbon fiber and high strength T700 carbon fiber were used. Through the study, we found that the curing agent with good flexibility can get freedom of curing high modulus, small free volume, low thermal expansion coefficient, good interface bonding properties, high tensile strength of the composite material. The interface performance is the important factors that affect performance of composite materials, good interface performance can give full play to the advantages of the resin matrix and fiber reinforced body. And we consider the differences of the thermal expansion coefficient between carbon fiber and resin matrix determines the mechanical properties of composite materials in a large part.In the experiment using, positron annihilation lifetime spectroscopy (PALS) test was used to study stoichiometric ratios and kinds of curing agent on the material internal structure. Through the analysis the influence of the material type and stoichiometric ratios on the crosslinking network structure and the properties of materials, we can provided reasonable design idea for selection for amine curing agent dosage and types and the preparation of high performance materials of reasonable design.