Relationship Between Single Fiber Contact Angle and Sizing Performance, 1994 Papermakers Conference Proceedings

Please Note: This document will be available in PDF format in the "My Electronic Documents" link on the home page once your order has been completed. Please make sure you have the latest version of Acrobat Reader. Click on the Acrobat Reader icon to check for the latest version, it’s FREE. To print a hardcopy of a PDF file correctly you must have a postscript printer. If you are not sure if your printer is a postscript printer please refer to your owner’s manual.

The Wilhelmy technique was used to measure single fiber advancing contact angles of water on pulp fibers treated with alkyl ketene dimer sizing (AKD). These measurements were compared to the sizing performance as determined by the HST and Cobb tests. The contact angle measurement is more sensitive to changes in the amount of AKD on the fibers than either sizing test. Sizing performance as measured by standard tests is dependent upon both sheet structure and fiber wettability. It was found that the single fiber contact angle was directly proportional to the AKD dosage, but in a nonlinear fashion. The advancing contact angle can be described by an empirical equation which incorporates a sizing response factor, òR. The magnitude for òR is indicative of the nature of the relationship between the contact angle and the dosage of AKD. The nature of AKD sizing was investigated by comparing single fiber contact angle measurements with AKD retention and reaction, revealing that the unreacted AKD does contribute to the hydrophobicity of the fiber. The difference in wet surface areas between hardwood and softwood pulps is theorized to be responsible for the industrial observation that hardwoods are easier to size than softwoods.