Pressure induced changes in liquid alkane chain conformation

Abstract

Conformations of n‐alkane molecules in the liquid state have been studied as a function of temperature and pressure using Raman scattering. Observations of conformationally sensitive Raman bands in hexane, heptane, octane, and hexadecane reveal no sign of the pressure‐induced effects in polyethylene. Instead the Raman intensities indicate chain kinking as a function of pressure—a dramatic effect in the shorter chains, a slight effect for hexadecane. A theory based on considerations of conformational energy and translational entropy is presented which explains these effects qualitatively.