Papers by Author: Yan He

Abstract: Normal thermal conductivity of amorphous and crystalline SiO₂ nano-films is calculated by nonequilibrium molecular dynamics (NEMD) simulations in the temperature range from 100 to 700K and thicknesses from 2 to 6nm. The calculated temperature and thickness dependences of thermal conductivity are in good agreement with previous literatures. In the same thickness, higher thermal conductivity is obtained for crystalline SiO₂ nano-films. And more importantly, for amorphous SiO₂ nano-films, thickness can be any direction of x, y, z-axis without effect on the normal thermal conductivity, for crystalline SiO₂ nano-films, the different thickness directions obtain different thermal conductivity results. The different results of amorphous and crystalline SiO₂ nano-films simply show that film thickness and grain morphology will cause different effects on thermal conductivity.

Abstract: Carbon black has been used as the main reinforcing fillers that increase the usefulness of rubbers. In this experiment, different compounds based on natural rubber were prepared with carbon black (N330) at various loading ratios from 10 to 125 phr. The mechanical and thermal properties of rubber compounds were measured and the test data with SEM micrographs were analyzed to determine the suitable ratio of carbon black for the desired properties of rubber compound. The results showed that carbon black particles were well dispersed in compounds with loading ratios of 25-30 phr, corresponding to maximum tensile strength values. While with the increase of carbon black content, heat conductivity kept sustained increase. Fractal dimension characterized the degree of uneven dispersion of carbon black in rubber fracture surfaces. A particular value of fractal dimension was obtained to characterize the optimum mechanical property of carbon black filled natural rubber. The thermal property and fractal dimension demonstrated same variation tendency.

Abstract: The heat conductive silicone rubber is prepared with methy1 viny1 silicone rubber as basic gum and SiCp (SiC particle), SiCp/SiCw (SiC whisker), graphite as heat conductive fillers. The effects of filler amount, filler shape, filler size and coupling agent on the thermal conductivity of silicone rubber have been studied in this article. The result shows that when the filling amount is increasing, the thermal conductivity of composite silicone rubber will increase too. There is no evident change for thermal conductivity with the small filling fraction, while the filling amount reaches a certain value, the thermal conductivity of composite increases obviously. Moreover, the thermal conductivity added with coupling agent (KH-602) is higher than that of composite without coupling agent addition.

Abstract: In this paper, the thermal conductivities and mechanical properties of natural rubber which is filled with graphite and modified by acrylate are studied experimentally. It is found that the thermal conductivities and mechanical properties of vulcanizates are improved significantly. The thermal conductivity and mechanical properties of graphite-filled nature rubber which is modified by the mass ratio of 5:1 between graphite and monomers are best in 3 kinds of formulations.