STP1414: The Physical Chemistry of Water Dispersible Granules, Part II: The Influence of Dispersant Molecular Weight and Paste Rheology on the Physical Properties of Extruded WDGs

    Doering, IW
    Industry specialist and manager, Agricultural Chemicals, Westvaco Corporation, Charleston, SC

    Delli Colli, HT

    Pages: 13    Published: Jan 2001


    Abstract

    The molecular weight distribution and the degree of sulfonation of Kraft lignin dispersants are used to determine performance plateau regions for the most favorable physical properties of WDG formulations produced by low pressure extrusion. Special emphasis is placed on the preparation of extruder feedstock pastes and on the related rheological properties of such pastes. Their ideal water requirement was determined by torque rheometry and other methods such as yield by deformation. A model study containing blends of high and low degree of sulfonation Kraft lignin dispersants with correspondingly high and low molecular weight fractions demonstrates the existence of such performance plateau regions which permit the selection of a final formulation with a broad spectrum of desirable physical properties. Porosity data are utilized to further demonstrate performance differences within the described platform regions.

    Keywords:

    formulation development, sulfonated Kraft lignin, degree of sulfonation, molecular weight distribution, extrusion, paste rheology, yield value, die expansion, pore size distribution, shelf life, dispersion, dispersional stability


    Paper ID: STP10721S

    Committee/Subcommittee: E35.22

    DOI: 10.1520/STP10721S


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