The method used to measure conductivity consisted of embedding resistance wire, around which thermocouple wire had been wound, in the wax. An electric current was passed through the wire and temperature rise was recorded as a function of time. The determination was repeated at various temperatures from 20 to 120 °C, i.e. in the solid and liquid states. The resulting conductivity-temperature curve has an S shape, like the curves for specific volume and most other physical properties of substances that are crystalline in the solid state. Equations for reduced thermal conductivity were applied. For the solid state external degrees of freedom could be calculated and the partially crystalline nature was confirmed. Experimental and predicted values for reduced conductivity of molten wax differed somewhat, probably because of persisting order in the liquid state. There is a retrograde tendency in conductivity above the melting point. According to the literature measurements on alkanes are likely to be subject to errors due to convection unless extreme precautions are taken. This effect could cause the retrogression.
J. H. Roux, Roy D. F. Smith, R. Turner
Journal of Applied Chemistry and Biotechnology