Mode of Action of Silicone Drift Control Agents

Using high-speed video techniques, the influence of diluted polyether siloxane emulsions on the breakup mechanism of liquid spray films was investigated. First, the fragmentation of a single drop in an air flow, the so-called bag breakup, was used as a model system to study the ability of the polyether siloxane emulsion to control the breakup process. What was learned from these model experiments was then transferred to spray experiments using classical agricultural flat-fan nozzles. These demonstrated that polyether siloxane emulsions cause the nucleation of holes in an expanding liquid film, which leads to an accelerated, more uniform, and earlier breakup. Image-based drop size measurements confirmed that the promoted lamella breakup in turn leads to a considerable reduction of drift-prone droplets in the spray. Low-speed wind tunnel spray studies were conducted in order verify the findings from the high-speed video experiments.