Influence of PVA and CMC on the Properties of Pigment Coating Colors and their Effects on Curtain Stability

Autor: Eun Heui Choi, Chae Hoon Kim, Hye Jung Youn, Hak Lae Lee
Jazyk: angličtina
Rok vydání: 2015
Předmět:
Zdroj: BioResources, Vol 10, Iss 4, Pp 7188-7202 (2015)
Druh dokumentu: article
ISSN: 7188-7202
1930-2126
DOI: 10.15376/biores.10.4.7188-7202
Popis: The influence of polyvinyl alcohol (PVA) and carboxymethyl cellulose (CMC) on the properties of ground calcium carbonate (GCC) and clay coating colors, as well as its effect on curtain stability during the coating process was investigated. Based on the experimental results of the zeta potential, sediment porosity, rheological measurements, the floc formation mechanisms of the cobinders were proposed. The zeta potential decreased with an increase in the amount of added PVA, while it barely changed when CMC was added. This was attributed to the adsorption of PVA onto the pigment surface, while the adsorption of CMC was hindered by electrostatic repulsion. CMC cobinder increased the low-shear viscosity, but it resulted in relatively low viscosity under high-shear conditions, indicating the disruption of the formed flocs under high shear. The destabilization mechanism of the curtain coating differed depending on the type of cobinder. The PVA cobinder flocculates the coating color via a gelling mechanism, while the CMC cobinder flocculates the colors via a depletion flocculation mechanism.
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