Preparation of CaCO 3 nanoparticle/pulp fiber composites using ultrafine bubbles

• Published in: Nordic pulp & paper research Vol. 35; no. 2; pp. 279 - 287
• Main Authors: Fuchise-Fukuoka, Moe, Oishi, Masatoshi, Goto, Shisei, Isogai, Akira
• Format: Journal Article
• Language: English
• Published: 25.06.2020
• ISSN: 0283-2631; 2000-0669
• DOI: 10.1515/npprj-2019-0078

Abstract In this study, CaCO 3 nanoparticle/pulp fiber composites were prepared by formation of ultrafine bubbles of CO 2 gas in aqueous Ca(OH) 2 solution containing beaten or unbeaten pulp fibers. Scanning electron microscopy images of the fiber/CaCO 3 composites showed that primary CaCO 3 nanoparticles with average diameters of 50–80 nm densely formed on the pulp fiber surfaces. The average sizes and morphologies of the precipitated CaCO 3 nanoparticles can be controlled by controlling the CO 2 flow rate into the pulp slurry. From dynamic drainage analysis of the CaCO 3 /pulp slurries with high shear force, retention of the CaCO 3 nanoparticles on the pulp fiber mats was ∼10 % higher for the slurry formed by the ultrafine bubble method than for that formed by mixing precipitated CaCO 3 and pulp fiber. Therefore, precipitated CaCO 3 nanoparticles stably formed on the pulp fiber surfaces in the slurry by the ultrafine bubble method. Compared with reference handsheets, handsheets prepared with the CaCO 3 nanoparticle/pulp fiber composites had higher CaCO 3 contents and had consequently higher specific surface areas and surface smoothness values. In contrast, the tensile strength and elongation at break decreased because the sheet density decreased with increasing CaCO 3 content in the handsheets.