Strength-enhancing effect of cationic starch on mixed recycled and virgin pulps

The present work focuses on the effect of cationic starch (Cat St) on the properties of handsheets made from recycled old corrugated container (OCC) and virgin neutral sulfite semi-chemical (NSSC) pulp. This study also evaluates the usage of OCC fibers as a supplement raw material for papermaking. The handsheet samples contained a series of mixtures of OCC and virgin NSSC pulp (0:100, 20:80, 30:70 and 40:60 by weight) and Cat St (0, 0.5, 1.2, 2 and 3 wt.%). The results showed that addition of Cat St could enhance all the strength properties of handsheets remarkably. At certain Cat St dosage, with increasing OCC fibers, the strength properties were improved significantly, which could be related to the Cat St adsorption efficiency. OCC fibers have more specific surface area than NSSC fibers; therefore, they could adsorb much more amounts of Cat St.