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|Keywords:||Pulp cellulose modification|
|Abstract:||The value and performance of Canadian premium NBSK pulps can be enhanced by attaching copolymers of maleic anhydride (MA) to the fiber surfaces, thus leading them to new applications. Kraft pulps can be treated with MA copolymers as it enters the pulp drying machine, where drying and heating results in polymer fixation. However, polymers capable of forming covalent linkages with cellulose tend to be good adhesives, dried market pulps usually cannot be redispersed (repulped). By carefully controlling the curing conditions (i.e., the time, temperature, and pH of the polymer solution) it is possible to fix MA copolymers to pulp fibers, while also maintaining repulpability. The impact of curing on repulpability can be probed by measuring the wet tensile indices of impregnated, cured pulp sheets. We have shown that the curing conditions can be condensed into a single parameter, the product , where is the estimated conversion of succinic acid moieties to the corresponding anhydrides during curing, and is the amount of added MA copolymers. A survey of the common commercial MA copolymers identified high molecular weight (Mw) PEMA (100-500 kDa) as the most promising option, as it is possible to graft 1 and 29 kg of PEMA to each tonne of dried untreated pulp in high yield while still maintaining repulpability. PEMA grafting enhances the properties of pulp and paper in many ways, including increasing fiber swelling, increasing adsorption capacity of cationic additives, and increasing wet and dry paper strength.|
|Description:||The thesis proposed technology to graft polymers to wood pulps.|
|Appears in Collections:||Open Access Dissertations and Theses|
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|Zhang_Hongfeng_202105_Doctoral Degree.pdf||This thesis describes technology to graft polymers to wood pulps.||4.89 MB||Adobe PDF||View/Open|
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