Study On Preparation Process Of Epoxy Resin (EP) Conducting Composites Material

The preparation process and properties of expended graphite (EG)-epoxy resin (EP) was studied in this thesis systemically. Through test of electrical resistivity and scanning electron microscope (SEM), we focus mostly on the things as follows:The optimum process condition and effect factor to prepare the composite by co-mixed method;The effect of the added nano-TiO₂ to the electrical resistivity of the composite;The effect of different preparing methods to the electrical resistivity of the composite;Non-ohm properties of the composite.The main conclusions are shown as follows:(1) The optimal process condition to prepare the composite by co-mixed method is: the critical value of EG is 6wt%; ethylene glycol diglycidyl ether is selected as the active diluent, and the optimal content is 15wt%; ethanol is selected as the inactive diluent, it is used to make good dispersion of EG; the optimum stirring time is 60min; whetting makes the decrease of the conducting properties but increase of the mechanical properties in theory; the addition of coupling agent makes the increase of the electrical resistivity of the composite when EG is in low content, but when the content of EG is high enough to fulfill the conducting path, there has little effect to the conducting properties; with the increase of expansion ratio of EG, the electrical resistivity of the composite increased when EG is in low content, and the whole decreased trend of the electrical resistivity of the composite is more obvious.(2) The addition of nano-TiO₂ makes increase the electrical resistivity of the composite, and this is more obvious when EG is in low content.(3) Composite prepared by three different methods: solution interaction method, co-mixed method and ultrasonic dispersion method, the conducting properties of thecomposite decreased in turn but the mechanical properties increased theoretically.(4) Through studies of non-ohm properties of the composite, it is found that there is a good linear relationship between lgR and lgU, and the reason to produce non-ohm properties probably conductive mechanism of tunnel effect and effect of electric field emission.