Study On Novel Modified Graphite/Polyurethane Electroconductive Adhesives

In view of the development trend and economical facts of the conductive material, the nano-Graphite is selected as the matrix recombination of conductive filler and polyurethane for this thesis, due to it's widely available and low cost. Eventually, nano-Graphite/polyurethane Electroconductive Adhesive will be researched and developed, which demonstrats superior performance on the conductivity and physical nature, moreover, which has heat resistant properties.The Electroconductive Adhesive is the composition of conductive filler, matrix material, curing agent and other auxiliaries. Expanded graphite is maid from aufblasbar graphite which must be swelled under high temperature.Via the ultrasonic's shocking and crushing, expanded graphite turns into nano-Graphite(NanoG). At next step, nano-Graphite is reducted by Hydrazine hydrate and turns into Reduced nano-Graphite(RNG). Oxided nano-Graphite (ONG)is made from nano-Graphite treated by oxidizer. We use the above modified graphite respectively as the conductive filler, Polyurethane(PU) and Polyurethane-Epoxy IPNs(PU/EP IPNs) as the matrix materials, 1,1,1-Tris(hydroxymethy)propane (TMP) as a curing agent and other additives. All these components are necessary for the novel modified graphite/polyurethane ECA series:NanoG/PU, ECA,ONG/PUⅠECA,RNG/PUⅠECA,RNG/PUⅡECA,RNG/PUⅢECA and NanoG/PU/EP IPNs ECA.In order to explore the hydrazine hydrate reduction method and the oxidation process, we use the X-ray energy dispersion spectrometer (EDX) to analysis the of oxygen element on the surface of the NanoG, RNG and ONG. By scanning electron microscope (SEM) to observe the morphology of modified graphite, it is possible to explore the relationship between the morphological character of conductive filler and the main applying performance of ECA. Using the standard digital multimeter (UT56) to estimate the volume resistivity (ρv) of ECA, and we can get the electrical property parameters—the conductivity(σ). We use the universal testing device (UTD) to test ECA's tensile-shear strength (T); By drawing the graph of ECA's TG and DTG curves with thermogravimetry analysis (TGA), we can get the thermal property parameter—the initial temperature of heat degradation (to) and the maximum weight loss rate (Dm).By the experiment, the conclusion is drawed out that:Nano-Graphite/Polyurethane Electroconductive Adhesive exerts more superior performance on the conductivity and physical nature and heat resistant properties than pure polyurethane matrix. Polyurethane adhesives electrical conductivity and heat resistant stability will become stronger with it's nano-Graphite content increasing. At the same time, it's physical nature will become stronger at the earlier stage and weaken at the later period.