Study On The Structure And Curing Kinetics Of CTBN/OMMT Modified Epoxy Resin

The properties of epoxy resins (EP) are closely related to the morphological structure of its curing products, therefore, the research on its curing process is required in order to obtain high performance materials. One-component modified epoxy resin has been studied more broadly and in depth than two-component one which is more complicated. In this article, carboxyl-terminated butadiene-acrylonitrile (CTBN) rubber and organoclay (OMMT) are used to modify the resin. The structure and curing kinetics of EP/CTBN/OMMT are studied, which gives a guide to the preparation of high performance EP/CTBN/OMMT composite.Two systems have been studied here. The first is CTBN modified EP. Curing samples with different CTBN concentrations were prepared, and their properties as well as structures were analyzed. The second is CTBN/OMMT modified EP. Solution method was chosen to prepare the CTBN/OMMT pre-intercalated composite, and then curing agent was added for curing. The dissertation consists with two parts. The first part presents the structure research of modified EP systems. The second analyzes the curing kinetics.Solution method was chosen to prepare CTBN/OMMT na no-composite. The influences of reaction temperature as well as ratio of materials to the exfoliation and intercalation of OMMT were studied with IR, XRD and TEM. It is shown that CTBN can intercalate into the layers of OMMT easily, which may increase the inter-layer distance. Three kinds of resin-based composites were prepared, namely EP/CTBN, EP/OMMT, EP/CTBN/OMMT, and their structures were also characterized as well as properties. The fracture surfaces were observed through SEM, and the rubbery domains were clearly seen in the CTBN-modified epoxy, while the addition of OMMT may inhabit the rubbery phase separation. The modified samples all remain good thermal resistance, especially samples with OMMT.The cure kinetics of modified epoxy was studied through non-isothermal scanning with a differential scanning calorimeter. A detailed process for OMMT-modified epoxy was demonstrated to show the determination of the kinetic model, calculation of the kinetic exponents and the pre-exponential factor with Malek’s method. Results show that the autocatalytic model can describe satisfactorily the kinetics of modified and unmodified curing, and the addition of CTBN or OMMT did not change the curing mechanism. The isoconversional method was used to calculate the activation energy of a set of conversions, which gave a clear guide for curing analysis.