STP943: Selection of Wetting Adjuvants

    McKay, BM
    Research associate, research technician, and senior chemist, FMC Corp., Princeton, NJ

    Koch, R
    Research associate, research technician, and senior chemist, FMC Corp., Princeton, NJ

    Herbert, RM
    Research associate, research technician, and senior chemist, FMC Corp., Princeton, NJ

    Pages: 5    Published: Jan 1987


    Abstract

    Wetting of crop foliage by aqueous emulsion sprays can be quantitatively described, and the conditions for perfect wetting can be predicted. An empirical relationship from the literature for wetting of high-energy organic surfaces has been found to be applicable to wetting of both broad leaves and grasses. A graph of the cosine of the spray droplet contact angle against the surface tension can be extrapolated to predict the surface tension necessary to achieve a zero contact angle (perfect wetting). Surfactants and emulsifiers typically used in pesticide formulations cannot reduce aqueous surface tension sufficiently to achieve a zero contact angle. Certain silicone and fluorocarbon surfactants were found to reduce aqueous surface tension sufficiently to produce a zero or near-zero contact angle.

    Keywords:

    wetting, contact angle, foliar sprays, silicone wetting adjuvant, fluorocarbon wetting adjuvant, critical surface tension


    Paper ID: STP19395S

    Committee/Subcommittee: E35.22

    DOI: 10.1520/STP19395S


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