Effect of Polystyrene Acrylic on the Rheological Properties of Washable Paints Produced From Jatropha Seed Oil

Abstract

Washable paints are less toxic due to the absence of organic solvent used in solvent based paints, but these paints were reported not to have excellent rheological properties as those of solvent based paint. This work studied the effect of polystyrene acrylic on the rheological properties of washable paints produced from jatropha seed (Jatropha curcas) oil. The oil was first converted to alkyd resin through alcoholysis and polycondensation reactions, and emulsified using isopropyl alcohol. Four samples of washable paints were produced using different quantities of alkyd emulsion and polystyrene acrylic in these combinations; 25% of polystyrene acrylic binder and 75% alkyd emulsion binder (JSO1P), 50% each for polystyrene acrylic and alkyd emulsion (JSO2P), a combination of 75% polystyrene acrylic binder and 25% of alkyd emulsion binder (JSO3P), and a control sample which contains only polystyrene acrylic binder (PSNA). These paint samples were analyzed for the following performances; storage stability, sagging behavior, leveling and applicator loading. These performances were determined through rheological properties which include dynamic viscosity, yield stress and shear rates. The dynamic viscosities were measured at three different shear rates; 06 rpm, 12 rpm, 30 rpm and 60 rpm respectively. The rheological study shows that the viscosity of produced paints is within the range of 107.1mPa.s to 104.4mPa.s. At different shear rates, the viscosity of JSO2P decreased from 1031mPa.s at 06rpm to 107.1mPa.s at 60rpm, that of JSO3P decreased from 1052mPa.s at shear rate of 06rpm to 106.6 at the shear rate of 60 rpm, and that of PSNA decreased from 1055.9mPa.s to 106.7mPa.s at the shear rate of 60 rpm. The yield stress obtained include; 10567.2mPa for JSO2P, 10812mPa for JSO3P and 10801.8mPa for PSNA. The performance results indicated that polystyrene acrylic can be used to modify the flow properties of washable paints, but this can only be achieved at a ratio above 25% of polystyrene acrylic to jatropha based alkyd emulsion.