Thermal Conductivity Of Epoxy Resin Composite Materials

Epoxy resin as a high performance polymer materials, had been widely used in practical production and daily life. There is a fatal flaw for epoxy resin, that is its thermal conductivity is very low, typically 0.2 W/(m ? K), which cannot be used in the application of electrical and plastic materials for thermal conductivity. In order to improve the thermal conductivity property of epoxy resin, present work designed and fabricated new type epoxy resin composite materials filled with carbon particle and construction of three-dimensional heat conduction pathway. Porous expanded graphite conductive filler, using a magnetic stirrer and casting molding process for the preparation of expanded graphite/epoxy composite(EP/EG). Open cell foam can be used as a natural heat conduction path and vacuum impregnation method was proposed for fabricating foam/epoxy composites. We use laser thermal conductivity meter, infrared characterization, TGA and SEM scanning methods to characterize different mixed conditions of EP/EG composites. The results show that wit h the increase of expanded graphite content, the performance of thermal conductivity of EP/EG composites increased. When the size is bigger and then the thermal conductivity properties can be higher. When the amount of filling is small, the changed range of the thermal conductivity is not obvious; thermal conductivity of the composite material will have a rapid rise with higher filling amount. When expanded graphite was treated with KH-550, the thermal conductivity, thermal stability and mechanical properties can be improved.In order to make the filler mixed in epoxy resin touch each other at low content to form a continuous heat conduction channel, the method of matching up in micro / micron and micron/nanoscale was used to investigate the ratio effect on thermal conductivity of materials. The results shown that for micro/micron grade(300 mesh and 100 mesh), with total mass fraction 20 wt% of epoxy monomers, the materials have almost the highest thermal conductivity about 0.97 W/(m·K) when the mix ratio is 1:2. The tensile properties of the material is higher than that purely filled with bigger EG, when the total percentage is 5 wt% for micron/nanoscale distribution, the thermal conductivity of material also have the highest level, about 0.28 W/(m · K) when carbon nanotubes account for 10 wt% of total filler. Acidification process of carbon nanotubes can make the thermal conductivity higher than that untreated.To prove that continuous heat conduction channel has great influence on thermal conductivity of materials. In this paper, three kinds of foams including copper foam with different diameter, titanium foam and graphite foam were impregnated with epoxy resin to research their thermal conductivity. For graphite foam with porosity of 76%, the thermal conductivity is as high as 92.126 W/(m·K). For copper foam with 0.2μm aperture whose volume ratio is only 6.77% of epoxy resin, the thermal conductivity of the composite reaches 9.912 W/(m·K). Compared the results of copper foams with different aperture. It can be found that the smaller the void is, the higher thermal conductivity materials can obtain. Thermal conductivity of the material depends on the parent thermal properties of fillers. For graphite foam with the same mass fraction of expanded graphite, the foam design has much higher thermal conductivity than EP/EG(0.31 W/(m ·K)). It can be concluded that the formation of the thermal channel for thermal conductivity has great impact on thermal conductivity. The outlook will be sumarrized in the conclusion.