Colloidal Behavior of Amphoteric Dry Strength Agents

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dc.contributor.advisor Dr. John A. Heitmann, Committee Member en_US
dc.contributor.advisor Dr. Dimitris S. Argyropoulos, Committee Member en_US
dc.contributor.advisor Dr. Martin A. Hubbe, Committee Chair en_US Sezaki, Takao en_US 2010-04-02T18:16:22Z 2010-04-02T18:16:22Z 2004-03-02 en_US
dc.identifier.other etd-11242003-160324 en_US
dc.description.abstract Dry strength additives are essential to produce paper that is strong enough to meet various usage requirements. Recently, amphoteric copolymers have been developed as more effective dry strength agents for addition during the papermaking process. To understand the mechanism of such polyampholytes, the fundamental colloidal behavior of amphoteric polyacrylamide dry strength additives was investigated. The present thesis includes potentiometric titrations, viscometric and turbidimetric measurements, charge analysis using microelectrophoresis and colloidal titration with a streaming current detector, and adsorption of amphoteric polyacryamides onto bleached kraft hardwood fibers. The potentiometric titration results for the polyampholytes were in agreement with the theoretical curves except in a range between pH 4 and 6. The charge analysis showed that the total charge of the amphoteric polyacrylamides depended on pH. The total net charge was reversed at the pH value termed the iso-electric point, where the polyampholytes have no net charge. The iso-electric points determined by the two measurements, microelectrophoresis and streaming current, coincided well, but not with the calculated values. Around the iso-electric point, the turbidity of the polyampholyte solution was maximized, while the viscosity was minimized. In this region of pH, addition of salt led to swelling of the polyampholyte chain conformation, which was an opposite effect from what is seen in simple polyelectrolytes (anti-polyelectrolyte effect). Namely, the turbidity was decreased and the viscosity was increased by addition of salt to the polyampholyte solution around the iso-electric point. A colloidal titration procedure using a streaming current technique was found to be applicable at either pH 3 or 11 in order to determine the concentration of the polyampholytes. The required titration amount for zero charge was found to deviate from a 1:1 stoichiometric relationship, depending on the salt concentration. The adsorption of the amphoteric polyacrylamide dry strength additives onto bleached hardwood fibers was significantly affected by the pH and salt concentration. Also, it was slightly increased with time for adsorption. The stirring rate during adsorption was not a important factor for adsorption. It was found that the polyampholytes with no net charge were also adsorbed on negatively charged fibers. The maximum adsorption of the polyampholytes was achieved around the isoelectric point. This behavior is attributed to a sufficiently low charge density of the polyampholytes around the iso-electric point, which does not allow the polyampholyte chains to lie flat against the charged surfaces because of electrostatic attractions. en_US
dc.rights I hereby certify that, if appropriate, I have obtained and attached hereto a written permission statement from the owner(s) of each third party copyrighted matter to be included in my thesis, dissertation, or project report, allowing distribution as specified below. I certify that the version I submitted is the same as that approved by my advisory committee. I hereby grant to NC State University or its agents the non-exclusive license to archive and make accessible, under the conditions specified below, my thesis, dissertation, or project report in whole or in part in all forms of media, now or hereafter known. I retain all other ownership rights to the copyright of the thesis, dissertation or project report. I also retain the right to use in future works (such as articles or books) all or part of this thesis, dissertation, or project report. en_US
dc.subject Dry strength en_US
dc.subject Colloidal titration en_US
dc.subject Microelectrophoresis en_US
dc.subject Adsorption en_US
dc.subject Turbidimetry en_US
dc.subject potentiometric titration en_US
dc.subject Viscometry en_US
dc.subject polyampholytes en_US
dc.subject amphoteric polyacrylamide en_US
dc.title Colloidal Behavior of Amphoteric Dry Strength Agents en_US MS en_US thesis en_US Wood and Paper Science en_US

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