polymers
Article Assessment of the Performance of Cationic Cellulose Derivatives as Calcium Carbonate Flocculant for Papermaking Jorge F. S. Pedrosa 1, * , Lu í sAlves 1 , Carlos P. Neto 2 , Maria G. Rasteiro 1 and Paulo J. T. Ferreira 1
1 University of Coimbra, CIEPQPF, Department of Chemical Engineering, P ó lo II, R. S í lvioLima, 3030-790 Coimbra, Portugal 2 Forest and Paper Research Institute (RAIZ), R. Jos é Estev ã o, Eixo, 3800-783 Aveiro, Portugal * Correspondence: jpedrosa@uc.pt Abstract: Cationic polyacrylamides (CPAMs) are usually used as filler retention agents in papermak- ing formulations. However, increasing environmental restrictions and their non-renewable origin have driven research into bio-based alternatives. In this context, cationic lignocellulosic derivatives have been attracting considerable research interest as a potential substitute. In this work, distinct cationic celluloses with degrees of substitution of between 0.02 and 1.06 and with distinct morpho- logical properties were synthesized via the cationization of bleached eucalyptus kraft pulp, using a direct cationization with (3-chloro-2-hydroxypropyl) trimethylammonium chloride (CHPTAC) or a two-step cationization, where the cellulose was first oxidized to form dialdehyde cellulose and was then made to react with Girard’s reagent T (GT). Fibrillated samples were produced by subjecting some samples to a high-pressure homogenization treatment. The obtained samples were evaluated regarding their potential to flocculate and retain precipitated calcium carbonate (PCC), and their performance was compared to that of a commercial CPAM. The cationic fibrillated celluloses, with a degree of substitution of ca. 0.13–0.16, exhibited the highest flocculation performance of all the cationic celluloses and were able to increase the filler retention from 43% (with no retention agent) to ca. 61–62% (with the addition of 20 mg/g of PCC). Although it was not possible to achieve the performance of CPAM (filler retention of 73% with an addition of 1 mg/g of PCC), the results demonstrated the potential of cationic cellulose derivatives for use as bio-based retention agents.
Citation: Pedrosa, J.F.S.; Alves, L.; Neto, C.P.; Rasteiro, M.G.; Ferreira, P.J.T. Assessment of the Performance of Cationic Cellulose Derivatives as Calcium Carbonate Flocculant for Papermaking. Polymers 2022 , 14 , 3309. https://doi.org/10.3390/ polym14163309
Keywords: calcium carbonate; cationic cellulose; fibrillated cellulose; flocculation; laser diffraction spectrometry; quaternary ammonium
Academic Editor: Francisco Javier Espinach Or ú s
1. Introduction In certain paper product formulations, a portion of the cellulose fibers is often partially replaced by mineral fillers (from now on, these will just be referred to as fillers), such as kaolin clay, talc, natural ground calcium carbonate (GCC) or synthetic precipitated calcium carbonate (PCC) [1]. Fillers, initially applied due to their lower price compared to cellulose fibers, are also used to improve a range of properties [2]. The use of fillers can improve the brightness and opacity of the paper, decrease the surface roughness (especially after calendaring), enhance the printing quality, improve the formation of the paper matrix by filling the voids between the fibers and also increase the dimensional stability of the paper, as they tend to remain inert when wetted, unlike cellulose fibers that can swell and retract [3]. These fillers present a typical particle size smaller than 4 μ m [2], being much smaller than the mesh size of the screen at the forming section of the paper machine. In fact, the screens with a mesh size ranging between 40 and 100 mesh (openings with a diameter in the 150 to400 μ m range) [4], although small enough to retain almost the totality of the cellulose fibers (with a length of around 2–5 mm for softwood and 0.3–1.5 mm for hardwoods) [5], are not sufficiently small to retain the filler particles, resulting in material losses.
Received: 13 July 2022 Accepted: 12 August 2022 Published: 14 August 2022
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Polymers 2022 , 14 , 3309. https://doi.org/10.3390/polym14163309
https://www.mdpi.com/journal/polymers
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