SYMPOSIA PAPER Published: 08 November 2018
STP161020170208

The Role of Interfacial Rheology in Agricultural Drift Control

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The importance of controlling spray droplet size in the minimization of spray drift in the application of agricultural chemicals is widely acknowledged. Self-emulsifying tank-mix additives are an important tool for achieving this control. Understanding how these additives work is key in developing products that are both more efficient and more effective. Certain aspects of the performance of emulsion-based additives are well understood. In particular, oil droplets have been shown to induce perforations in the sheet emerging from a spray nozzle. The growth of these perforations results in the formation of a web that then shatters, creating spray droplets. Fragmentation closer to the nozzle outlet is believed to cause the generation of larger spray droplets. It has been suggested that the properties of deformable oil-phase droplets are important, while in general solid particles are ineffective in reducing drift. Beyond these details the mechanism of spray formation from tank mixes containing emulsions is not well understood. In this study we evaluated the relations between oil-droplet rheology and spray quality for tank-mix and model systems. In particular, we used an optical tensiometer equipped with a pulsating drop module to measure the effects of individual tank-mix components on the dilatational rheology of paraffinic and seed-oil droplets. Spray patterns of these systems were evaluated in a vertically oriented low-speed wind tunnel using industry-established laser-diffraction and imaging techniques. The correlation between these properties are presented.

Author Information

Penfield, Kevin
Croda Crop Care, New Castle, DE, US
Dempsey, Logan
Croda Crop Care, New Castle, DE, US
Wall, Jason
Croda Crop Care, New Castle, DE, US
Sun, Susan
Croda Crop Care, New Castle, DE, US
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Details
Developed by Committee: E35
Pages: 127–135
DOI: 10.1520/STP161020170208
ISBN-EB: 978-0-8031-7666-9
ISBN-13: 978-0-8031-7665-2