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6597740 
Journal Article 
New information on the role of cofactor in PEO-type retention aid systems 
Gibbs, A; Yang, Z; Xiao, HN; Pelton, R; , 
1997 
PIRA 
LEATHERHEAD 
Fundamentals of Papermaking Materials 
1135-1160 
English 
The flocculation of three colloidal dispersions (precipitated calcium carbonate (PCC), TiO2 and a calcined clay) using a combination of polymeric flocculants and cofactors was investigated. The flocculants used were PEO (MW = 9x10(6)), CPAM (a cationic copolymer of acrylamide) and POLYPAM-CO-PEG (a non-ionic comb copolymer (MW = 5x10(6)) consisting of a polyacrylamide backbone with similar to 1 mole % pendent PEG chains). The cofactors were based on poly(vinyl phenol-co-sodium acrylate) and poly(vinyl phenol-co-sodium styrene sulfonic acid). The amount of flocculation induced was dependent on the components present in each system. Cofactors containing sulfonic acid were more calcium ion tolerant than the cofactors containing carboxyl groups. These latter cofactors formed a precipitate when exposed to greater than or equal to 0.6 mM Ca++, Maximum flocculation of PCC was obtained by using POLYPAM-CO-PEG with a cofactor containing 23 mole % of sulfonated groups. TiO2 was not flocculated when PEO was employed due to the adsorbed layer thickness of this flocculant being approximately equal to half the Debye screening length in 0.001 hi NaCl. However, TiO2 was flocculated by POLYPAM-CO-PEG and CPAM, the best flocculation being obtained when POLYPAM-CO-PEG was used with either a cofactor containing 19 mole % sulfonated groups, or a cofactor containing 14 mole % acrylic acid groups. Overall, the easiest colloid to flocculate was the calcined clay; maximum flocculation being obtained when PEO was combined with a cofactor containing 19 mole % sulfonated groups. 
Calcium carbonate; Clay; Cofactor; Enhancer; Flocculant; Hydrogen bonding; Polymer; Retention; TiO2 
Baker, CF; 
1-85802-210-X 
11th Fundamental Research Symposium in the Fundamentals of Papermaking Materials 
CAMBRIDGE, ENGLAND