The effect of borax-modified starch on wheat straw-based paper properties.

This study was focused on the improvement of mechanical strength properties of wheat straw-based paper through modification of wet-end cationic starch with borax. Borax has been used extensively in many industrial applications for its unique physical and chemical properties. We investigated the strengthening effect of borax-modified starch (BMS) as wet-end paper strength additive on the mechanical strength properties especially the tensile strength of wheat straw-based paper. Hand-sheets made of typical wheat straw-based papermaking furnish were investigated. Experimental results showed that BMS substantially increased the strength properties. Tensile index, elongation, tensile energy absorption, and wet tensile index were increased by 17%, 23%, 20%, and 21%, respectively. A short mill trial was also conducted on papermaking machine in which the impact of BMS on wheat straw-based low grammage paper (<90 gsm) was investigated. The objective of mill trial was to reduce costly virgin softwood pulp content in wheat straw-based paper recipe. Mill trial results showed similar trends in strength properties as in case of laboratory studies. Virgin softwood pulp was reduced from 30% to 25% in papermaking furnish. Furthermore, no sheet breaks were reported during trial which often happened due to poor strength of paper web. This study strongly suggests that modification of wet-end cationic starch with borax holds a tremendous potential as wet-end strength additive. It can provide significantly improved strength properties, reduction in softwood pulp costs, and better papermaking machine performance. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013 [ABSTRACT FROM AUTHOR]