Thermal Polymerization of Drying Oils

Abstract

A statistical analysis of the thermal polymerization of drying oils has been made, and equations have been derived which predict the amount of a specific polymer present as a function of the extent of reaction and the original composition of the oil. Several samples of oils have been heat bodied to test the validity of this analysis. Certain discrepancies are apparent. The presence of an intrapolymer is postulated to explain these discrepancies. Indirect evidence for the presence of such a compound is presented. Additional studies of the heat polymerization of drying oils have been made by conducting the polymerization in dilute solution. After the reaction has been carried out, the solvent is removed and the properties of the oils compared with oils similarly treated without solvent. It has been found that iodine values of the oils are substantially the same regardless of the concentration of oil, and depend only on the time and temperature of heating, but that the viscosity decreases with lower concentration of the oils. This behavior substantiates the formation of an intrapolymer. By using the values at various concentrations it may be possible to estimate the extent of intrapolymer formation in heat bodied oils.