Estudo comparativo entre os parâmetros reológicos de tintas acrílicas arquitetônicas

Abstract

Acrylic paints are widely used in construction for providing protection and color. In order to ensure their performance at the different conditions of service (shear) to which they are submitted to, their rheology can be studied. A study was carried out with six commercial paints, classified as Economy, Standard and Premium, from two manufacturers (A and B), under the dilutions, by volume, of 0%, 10% and 20%. Flow tests, frequency sweep tests and thixotropy tests were performed. For the flow curves, there was relevant variability on apparent viscosity for values up to the shear rate of 1 s -1 . Standard Paints were less likely to sediment and sag, due to their high apparent viscosity at low shear rates. As per the thixotropy characterization, it was observed that the paints from manufacturer B were quicker to recover the initial viscosity after subjected to a high shear rate. An association between the yield of the paints, which is a practical indicator used in industry, and the apparent viscosity at 3000 s -1 (R 2 = 86%) was demonstrated. The frequency sweep showed that the Premium paints were less stable, due to their high loss modulus (G”). It is concluded that rheology is a useful and necessary tool to enhance understanding of paint behavior and adapt them to use and application.