Comparative study of the oxidation and polymerization of linseed oil by application of some recently developed physical techniques

Abstract

Summary Three physical test methods for drying oils have been described. They are: Molecular weight determinations in cyclohexane for thermally polymerized and mechanically oxidized oils. Results have been compared with those obtained in benzene. Theoretical and factual reasons have been given for the apparent validity of average molecular weight determinations in cyclohexane. Dielectric constant determinations for treated oils. It has been shown that the dielectric increases as an oil is oxidized but that no increase in dielectric occurs on thermal polymerization. The dielectric constant is mainly a function of the oxygenated structure of the oil. Power factor determinations. The power factor increases on polymerization and on oxidation. The values obtained for any given viscosity are considerably greater for the oxidized samples. Molecular weight and dielectric constant determinations have been used to advantage in our plants and laboratories. Our knowledge on power factor determinations, however, is as yet not extensive but it is felt that with more background data on this constant a potentially meaningful tool for oil evaluation can be developed.

A Dielectric Study of the Autoxidation of Ethyl Sorbate

“…This method has been used to study the autoxidations and polymerizations of various hydrocarbons and oils. [3][4][5][6][7][8][9] In many cases the change in dielectric constant has been shown to be an accurate measure of oxidation ; the slope of the curve was generally dependent on the experimental conditions. In most of the autoxidations studied, the dielectric constant increased along with the viscosity, refractive index, specific gravity, acid number and molecular weight; the iodine number may increase or decrease depending on the particular substances involved in the reaction.…”