Determination of melting point of n-alkanes by means of light scattering technique

Abstract

A modified droplet technique, an optical method, was used to determine the melting temperature of several n-alkanes. The authors prepared emulsions of n-alkanes in water by means of ultrasound dispersing without the use of surfactants. The average size of the paraffin cluster measured by dynamic light scattering had a radius of about 100 nm for all the samples. During heating, n-alkanes in the emulsion melt changing the optical properties of the emulsions. The sharp variation of light scattering intensity for a relatively small change in temperature corresponds to a phase transition of the n-alkane. Using the described principles, the authors determined the melting temperatures for n-alkanes from C19H40 (n-Nonadecane) to C28H58 (n-Octacosane). The obtained results are in good agreement with data of other works.