SYMPOSIA PAPER Published: 01 January 1999

Modification of Release Rate of Encapsulated A.I. Through Fluid Selection


Microencapsulation is one of the most important ways to control the release rate of a pesticide. Such a technology provides many advantages, such as an adjustable release of the core active ingredient (a.i.), stabilization against degradation of the pesticide, reduced toxicological properties and environmental impact. The release rate of an encapsulated pesticide can be modified, according to the requirements of the application, through fluid selection. Some fluids contribute to accelerate the delivery of liquid or solid a.i., others slow it down.

Several microcapsule formulations have been prepared with a selection of fluids (solvents), while keeping the other capsule parameters constant. The results reported in this paper demonstrate that the fluid, chosen among dearomatized and isoparaffinic hydrocarbons, aromatic hydrocarbons, acetate derivatives and blends of these, significantly influences: - The residual efficacy of Chlorpyrifos on cockroaches — The extent of growth inhibition of fungi by Propiconazole — The diffusion of the a.i. through rat skin.

By matching the biological control patterns with the expected dermal toxicity of a formulation, the formulator can select the specific fluid that better suits his requirements.

Author Information

Verbelen, RA
Lemoine, S
Basic Chemicals and Intermediates Technology, Exxon Chemical Europe, Machelen, Belgium
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Developed by Committee: E35
Pages: 65–80
DOI: 10.1520/STP14283S
ISBN-EB: 978-0-8031-5411-7
ISBN-13: 978-0-8031-2622-0