Zhang, Yumiao creator Nazhad, Mousa M. Chairperson Retulainen, Elias Examination committee Ruhanen, Mauno Examination Committee Government of Finland Scholarship Donor Asian Institute of Technology Scholarship Donor text series technical report th Bangkok Asian Institute of Technology 2002 continuing eng 55 leaves Anionic substances originating from pulping or coating processes accumulate in paper machine system and interfere with process chemicals, leading to increasing costs for paper production. The influence of three types of anionic trash on retention and sizing was investigated in laboratory scale. The sources of anionic trash were HW, SW and coated broke filtrate. The stock consisted of 85% HW, 15% SW and 20% PCC filler (on fiber weight). Retention aid was cationic polyacrylamide (C-PAM), and sizing agent was alkyl ketene dimmer (AKD). Effects of adding anionic trash catcher were also studied. Poly aluminum chloride was preferred as an anionic trash catcher due to its superior charge neutralizing ability. It was found that the existence of anionic trash influenced both retention and sizing. Coated broke filtrate contained much more concentrated anionic trash than HW and SW filtrate, and the way it interfering the retention aid and sizing agent was much complicated. PAC was effective in the case of neutralizing the anionic trash from HW and SW filtrate. No significant improvement of retention could be seen in the case of coated broke group even with adding PAC. In the case of AKD sizing, water resistance of HW group had a significant improvement due to charge neutralization by PAC. However, PAC showed little effects in SW and Coated broke groups. A thesis submitted in partial fulfillment of the requirements for the degree of Master of Science. Thesis (M.Sc.) - Asian Institute of Technology,2002 Paper coatings Additives Paper chemicals Asian Institute of Technology. http://203.159.5.9/ait-thesis/detail.php?q=B07366 http://203.159.5.9/ait-thesis/detail.php?q=B07366 030124 20260818143146.0