Formulators understand that improved application can be achieved by modifying the shear rheology of paint to be somewhat pseudoplastic and thixotropic. Axalta Coatings has been interested to find methods to measure extensional rheology that we believe more directly relates to paint atomization. When these methods are fully developed, we believe formulators can more precisely tune paint rheology for optimal application. Studies using the Capillary Breakup Extensional Rheometer (CaBER) have been used to demonstrate capillary thinning and filament formation. This is consistent with observed droplet formation during paint spray (e.g., high speed photos of rotary atomizers). We recognize some limits to this approach as a result of relatively low relaxation times observed in commercial paints.
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