Development of an ASTM Method for Measurement of the Extensional Viscosity of Agricultural Spray Solutions

    Volume 4, Issue 3 (March 2007)

    ISSN: 1546-962X

    CODEN: JAIOAD

    Published Online: 7 May 2007

    Page Count: 8


    Dexter, Robin W.
    Senior Formulations Technologist, FMC Corporation, Agricultural Products Group, Princeton, NJ

    (Received 27 October 2005; accepted 5 February 2007)

    Abstract

    Polymeric drift control agents are used to modify the droplet size distribution of pesticide sprays. These agents function by increasing the extensional viscosity of the spray liquid, enabling it to resist disruption as it emerges from the spray nozzle, usually leading to an increase in the median droplet diameter of the spray droplets. Extensional viscosity is often the most important physical property controlling the spray droplet size, especially when soluble polymers are present, but methods available for measurement of extensional viscosity of dilute solutions are complicated and are not generally available. This paper describes a simple, portable apparatus that can detect and quantify a relative extensional viscosity (screen factor) that is useful in evaluating the properties of drift control agents. The apparatus has been used to determine the screen factors of test substances used by the Spray Drift Task Force and to correlate them with independent measurements of extensional viscosity obtained using a Rheometrics RFX Extensional Rheometer. The method has been adopted as ASTM Method E 2408-04, “Relative Extensional Viscosity of Agricultural Spray Tank Mixes.”


    Paper ID: JAI100394

    DOI: 10.1520/JAI100394

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    Author
    Title Development of an ASTM Method for Measurement of the Extensional Viscosity of Agricultural Spray Solutions
    Symposium Pesticide Formulations and Delivery Systems: 27th Symposium, 2006-10-26
    Committee E35