Variation of flow birefringence with temperature in some liquid n-alkanes

Abstract

Flow birefringence measurements have been carried out on nine liquid n-alkanes over the temperature range 15–50°C. Five of these liquids have been investigated previously but at one temperature; results on the remainder represent new determinations. Our results invalidate a proposal that the optical polarizability parameter Γ is negative. The experimentally-determined temperature variations of Maxwell constant are compared with those calculated from the Raman-Krishnan theory and reveal a molecular weight anomaly in the region of the member n-tetradecane (C₁₄H₃₀). A qualitative explanation is proposed in terms of the presence of rotational isomers and their deformation in flow.