The Determination of the Solubility Parameter (δ) and the Mark-Houwink Constants (K & α) of Food Grade Polyvinyl Acetate (PVAc)

Abstract

Polyvinyl alkyl ester of carboxylic acids are a family of macromolecules in which the side chain esters (pendant groups) increase in molar mass and hydrophobicity and decrease in structural polarity as the number of carbons in the carboxylic acid increases. The most important polymer in this family is Polyvinyl Acetate (PVAc). The Solubility Parameter (δ) is a unique physical property of any polymeric material and can be a useful guide to understanding the miscibility or compatibility of two polymeric substances. It is therefore essential in working with polymeric blends of PVAc that the experimental solubility parameter be accurately and precisely known. We have experimentally determined the solubility parameter of food grade PVAc by measuring the intrinsic viscosity of several different molecular weight PVAc samples (ranging from 11K -75K Daltons) in four different solvents (acetone, methanol, tetrahydrofuran, toluene,) at 25°C using glass capillary viscometry. We also estimated the solubility parameter using the principles of group additivity contribution due to the atoms, groups and bonds present in PVAc based on the theories of Small, Hoy, and Van Krevelen. The Mark-Houwink constants for PVAC in the four solvents were also experimentally determined. Our experimentally determined solubility parameter was 9.35 (cal/cm3)1/2 which compared well with the computational values obtained by Hoy (9.56), Small (9.45) and Van Krevelen (9.27).