PRESSURE-INDUCED CHANGES IN LIQUID ALKANE CHAIN CONFORMATION

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. © 1979 American Institute of Physics.