Adding polyethylene oxide (PEO) at the wet end of a paper machine, can result in an increase in retention of the fine particles. The results obtained with PEO and the cofactors (SNS, MPR, and CAR), are discussed in terms of the association-induced polymer bridging mechanism. / Dynamic Light Scattering (DLS) of polymer solutions revealed that each of the three cofactors are forming complexes with PEO. CAR radically increased the apparent diameter of the PEO chains, and MPR seems to decrease it. In latex suspensions, the SNS was found very efficient in the sequence latex-polymer-cofactor (LPC), increasing the PEO hydrodynamic layer thickness (HLT). / Flocculation experiments with the help of a Photometric Dispersion Analyser (PDA), with PEO only (no cofactor) suggested that the fines are composed of more than one component. SNS was found to make all the fines alike by adsorbing on them. Adding the PEO after SNS gave homoflocculation. As a result, the specific surface of fines, calculated by PEO adsorption was found to be 0.223 m$ sp2$/g. / The association-induced polymer bridging mechanism can happen in three different manners depending if the cofactor and the polymer are adsorbing onto fines. When neither of PEO nor cofactor adsorb onto the collector, the PEO/cofactor association-complexes bridge the particles (van de Ven and Alince (1996)). When the cofactor (e.g. SNS) and the polymer adsorb onto the fines, in the sequence fines-cofactor-polymer (FCP), with a chemical ratio cofactor/PEO of 3/1, adsorption of the PEO chains onto cofactor-coated fines is likely to occur at the beginning followed by the flocculation of the fines. In the sequences fines-polymer-cofactor (FPC), when the polymer adsorbs onto the fines and the cofactor adsorbs (e.g. SNS) or not (e.g. MPR), a reenforcement of the bondstrength was noticed. (Abstract shortened by UMI.)
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:QMM.24053 |
| Date | January 1996 |
| Creators | Carignan, Alain. |
| Contributors | Garnier, G. (advisor), Ven, T. G. M. van de (advisor) |
| Publisher | McGill University |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Format | application/pdf |
| Coverage | Master of Engineering (Department of Chemical Engineering.) |
| Rights | All items in eScholarship@McGill are protected by copyright with all rights reserved unless otherwise indicated. |
| Relation | alephsysno: 001538224, proquestno: MM19863, Theses scanned by UMI/ProQuest. |
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