Paper Title
Retention Enhancement of Precipitated Calcium Carbonate and Nano Calcium Carbonate in Paper using Polyacrylate and Polyacrylamide

The aim of this work is to study the optimum usage of sodium polyacrylate (NaPA) and cationic polyacrylamide (CPAM) in order to enhance retention of filled, calcium carbonate. There were two calcium carbonate fillers to be employed; precipitated calcium carbonate (PCC) and nano calcium carbonate (NCC). CPAM was used as retention aid whereas NaPA acted as a dispersant, exhibiting dispersing ability. The pulp was mixed chemical wood pulp, with a hardwood/softwood ratio of 70:30 (percentage weight) and then beaten to 32525 mL CSF. The PCC and NCC suspension were separately added to the pulp stock. After the suspension was homogenously blended, both NaPA and CPAM were added. The amount of addition of each additive was optimized. Total filler retention of 30% was expected. Optical properties including whiteness, brightness and opacity were examined. The addition of CPAM significantly benefit filler retention, especially when using at 1.1 wt.%. In contrast, NaPA decreased filler retention particularly in NCC containing suspension due to excessive deagglomeration, even CPAM itself could not efficiently play its role. However, the improvement of optical properties of the paper sheet with NCC was observed and reported. Keywords - Dispersant, Nano calcium carbonate, Papermaking, Precipitated calcium carbonate, Retention aid.