PAPERmaking! FROM THE PUBLISHERS OF PAPER TECHNOLOGY Volume 2, Number 1, 2016
Improvement in the Retention and Strength of Paper Made from White- grade Wastepaper White ledger is white-grade recycled pulp that replaces the bleached kraft pulp (BKP) that typically forms the top ply of duplex boards. However, sheets made from white ledger are inferior in strength compared with those made from virgin pulp. Therefore, it is necessary to select a proper additive in order to overcome the disadvantages of using white ledger. In this study, the physical properties of white ledger used at a mill that produced duplex boards were analysed. The effect of cationic polyacrylamides (C-PAMs) with different charge densities and molecular weights on first-pass retention and paper strengths was simultaneously measured. White ledger contains fibre fines and filler fines, which reduced the strength of paper made from white ledger compared with paper made with BKP. This indicates that the improvement of first-pass retention and paper strength is important when the amount of white ledger increases in the top ply of a duplex board. The charge density of CPAM, which acts as a retention aid, is more important than its molecular weight in terms of improving the first-pass retention and paper strength of white ledger. The charge density of C-PAM must be high enough to catch anionic fine particles. Ji Young Lee,a Eun Hye Kim,b and Yong Joo Sung c,* Contact information: a: Department of Environmental Materials Science/IALS and b: Department of Forest Products, Gyeongsang National University, Jinju 52828, South Korea; c: Department of Biobased Materials, College of Agriculture and Life Science, Chungnam National University, Daejeon 34134, South Korea; * Corresponding author: yosung17@cnu.ac.kr . Article submitted: January 26, 2016; Peer review completed: March 18, 2016; Revised version received: March 25, 2016; Accepted: March 31, 2016; Published: April 13, 2016. DOI: 10.15376/biores.11.2.4718-4726 www.bioresources.com BioResources 11(2) 4718-4726 The Paper Industry Technical Association (PITA) is an independent organisation which operates for the general benefit of its members – both individual and corporate – dedicated to promoting and improving the technical and scientific knowledge of those working in the UK pulp and paper industry. Formed in 1960, it serves the Industry, both manufacturers and suppliers, by providing a forum for members to meet and network; it organises visits, conferences and training seminars that cover all aspects of papermaking science. It also publishes the prestigious journal Paper Technology and the PITA Annual Review , both sent free to members, and a range of other technical publications which include conference proceedings and the acclaimed Essential Guide to Aqueous Coating .
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Article 1 – Improving Retention and Strength
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