Preparation and application of chemically modified kaolin as fillers in Egyptian kraft bagasse pulp

The application of kaolin modified with hemicellulose and carboxymethyl cellulose (CMC) in the presence of alum (Al2(SO4)3) as fillers in Egyptian kraft bagasse pulp was investigated. The kaolin content was 15% based on pulp and different amounts of alum i.e., 2, 4, 8, 12, 16, 18 and 20% based on filler were added. It was found that kaolin modified with CMC/alum could improve the physical properties of handsheets. The modification of kaolin with hemicellulose and CMC/alum could enhance significantly the physical properties of handsheets as well as the amount of the retained kaolin. The retention, the brightness and the opacity of the handsheets filled with modified kaolin were significantly improved compared with either the control handsheets or that filled with unmodified kaolin. SEM observations of the fillers confirmed the surface encapsulating effect of the modifiers on the filler. It can be deduced also from the obtained images of the paper-sheets that modified filler particles were more effectively adhered and bonded to the pulp fibers, in comparison to unmodified filler particles. The results indicated that the interaction of hemicellulose and CMC could be used as a source for production of a good retention aid in papermaking.