A new theoretical equation for thermal conductivity of two‐phase systems

A new theoretical equation that describes the thermal conductivity of two-phase composite materials has been proposed. The Cheng-Vachon equation has been modified by introducing a new parameter named Pd max, permitting the new equation to describe the thermal conductivity of composite materials for a wide variety of filler shapes and states of dispersion. The new equation can describe the thermal conductivity of two-phase materials more accurately than any of the previous equa- tions. Furthermore, this new equation will make it possible to evaluate the dispersion state of the discontinuous phase by measuring the thermal conductivity of the filled polymers or the polymer blends. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 72: 1689 -1697, 1999