Applied rheology and architectural coating performance
A new review in part discusses the use of controlled-stress rheometry to characterise coatings, and presents ways of applying the results effectively to the analysis of paint flow.
The methodology is fundamental but not unduly time-consuming, since the objective is to provide sound yet timely guidance to formulators. Thirteen commercial semigloss latex paints were analysed rheologically to develop correlations to paint performance. Using the method of shear stress mapping, key regions of the non-equilibrium flow curve are identified for the control of paint flow processes. With this approach, simple but strong correlations were obtained of paint flow metrics to viscosity chosen at the relevant stresses.
Shear stress instead of shear rate as variable for viscosity data
The fact of high correlation means one can expect that an appropriate viscosity adjustment will correspondingly improve performance. It is argued that shear stress, not shear rate, is the correct independent variable both for experimentation and for the graphical presentation and analysis of viscosity data. The yield stress parameter, particle flocculation, and sedimentation are also discussed, and an oscillatory shear method of direct measurement of yield stress is described.
The study is published in: Journal of Coatings Technology and Research March 2019, Volume 16, Issue 2, pp 263–305.
