How to increased thermal conductivity of rubber compound.

Thermal conductivity is the basic parameter for defining heat flow in a material. Normally the thermal conductivity of rubber compound is inversely propertional to temperature but in the range of 20-90*C, the value of thermal conductivity of both gum and carbon black filled compound are slightly changed, therefore it can be assumed that the thermal conductivity of rubber is independent of temperature without any significant error. The inclusion of filler has a marked effect on thermal conductivity of the rubber compound which postulated that 10 phr of carbon black may be expected to increase the thermal conductivity by about 17% at room temperature. In the meantime we founded that thermal conductivity was an additive property depending on the volume fraction of the ingredient by an appropriate conductivity and adding these product to the thermal conductivity of gum vulcanisate. A large dependence of conductivity on loading of carbon black was reported that thermal conductivity of rubber compound increased almost linearly with black content in the range of 10-50 phr. An experimental result clearly showed that thermal conductivity increased linearly with carbon black loading and therefore the mathermatical relations between thermal conductivity and carbon black loading were introduce as

k(w) = k(0) + 0.32w

or

k(j) = k(0) + 0.4jf

where w is the weight fraction and j is the volume fraction of crabon black.

Apart from carbon black loading carbon black structure seems to have an influence on the thermal conductivity of rubber as well. Effect of carbon black structure on thermal conductivity of NR compound we found that higher carbon black structure gives higher value of thermal conductivity. However the degree of change in thermal conductivity as a function of carbon black structure is small and is not straight forward.