Introduction

Thermal conductivity (k), is the property of a material that indicates its ability to conduct heat. Conduction will take place only if there exists a temperature gradient in a solid (or stationary fluid) medium. Heat moves along a temperature gradient, from an area of high temperature and high molecular energy to an area with a lower temperature and lower molecular energy. Conductive heat flow occurs in direction of the decreasing temperature because higher temperature is associated with higher molecular energy. This transfer will continue until thermal equilibrium is reached. The rate at which the heat is transferred is dependent upon the magnitude of the temperature gradient, and the specific thermal characteristics of the material. Thermal conductivity is quantified in the units of W/mK, and is the reciprocal of thermal resistivity, which measures an objects ability to resist heat transfer. Lee’s method is used to measure the thermal conductivity of a poorly conducting material, such as glass, wood, or polymer. This was one of the earliest methods used to measure thermal conductivity that gave reliable results and is a steady state method.