Coefficient of thermal expansion of solid cyclohexane by means of dielectric constant measurements

Abstract

A method has been devised to measure the coefficient of thermal expansion of solid cyclohexane from −80 to 0 °C by means of dielectric constant measurements in a spring-loaded apparatus. Assuming the Clausius–Mosotti equation to be valid, the coefficient of thermal expansion is given by[Formula: see text](∂ε/∂T)_p for solid cyclohexane is found to be −9.6 × 10⁻⁴°C⁻¹. Therefore, α = 6.0 × 10⁻⁴°C⁻¹ at −40 °C and (∂α/∂T)_p = 6.4 × 10⁻⁷°C⁻².According to Crowe and Smyth (∂ε/∂T)_p is +7 × 10⁻⁴°C⁻¹ because it has been measured with a fixed amount of solid cyclohexane between the electrodes. Using a model calculation based on the equivalent circuit consisting of 3 series capacitors filled alternately with air and sample, it is shown that the apparent value of (∂ε/∂T)_p actually changes sign.