Structure and Strength of Flocs of Precipitated Calcium Carbonate Induced by Various Polymers Used in Papermaking

Because of persistent economic pressure on cost reduction, inorganic fillers such as precipitated calcium carbonate (PCC) have become increasingly economically attractive in the papermaking process. The increase of filler level in paper can be achieved by adding it to pulp prior to the headbox, eith...

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Bibliographic Details
Published in:Industrial & engineering chemistry research 2015-06, Vol.54 (24), p.6234-6246
Main Authors: Gaudreault, Roger, Di Cesare, Nicolas, van de Ven, Theo G. M, Weitz, David A
Format: Article
Language:English
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Summary:Because of persistent economic pressure on cost reduction, inorganic fillers such as precipitated calcium carbonate (PCC) have become increasingly economically attractive in the papermaking process. The increase of filler level in paper can be achieved by adding it to pulp prior to the headbox, either as individual filler particles or as preaggregates, while maintaining paper strength and minimizing their negative impact. Consequently, the floc structure and strength of PCC aggregates was studied using flocculants and dry strength agents, using static light scattering/diffraction (SLS), real time fluorescent video imaging (RTFVI), image analysis, photometric dispersion analysis (PDA), and scanning electron microscopy (SEM). It was found that PEO/cofactor induced PCC aggregates were weaker at high shear and far more irreversible than those induced by the partially hydrolyzed polyvinyl formamide copolymerized with acrylic acid (PVFA/NaAA) or cationic starch. Flocs produced at low polymer dosages were smaller and weaker than those produced at higher dosages. The number of discrete PCC particles in aggregates was measured using real time fluorescent video imaging combined with image analysis. Finally, we speculate that when two scalenohedral crystal type PCC particles aggregate, there is a small effective surface area to bind them, mainly through classical bridging or charge neutralization flocculation. Moreover, additional polymer adsorption results in higher coverage of the external and internal surfaces and prevents further aggregation due to electrosteric repulsion.
ISSN:0888-5885
1520-5045
DOI:10.1021/acs.iecr.5b00818