SYMPOSIA PAPER Published: 01 January 2001

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


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.

Author Information

Doering, IW
Agricultural Chemicals, Westvaco Corporation, Charleston, SC
Delli Colli, HT
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Developed by Committee: E35
Pages: 99–111
DOI: 10.1520/STP10721S
ISBN-EB: 978-0-8031-5459-9
ISBN-13: 978-0-8031-2891-0