Effect of Chitosan Electrostatic Charge on the Performance of Chitosan-Nanosilica in Recycled Old Corrugated Container Pulp

Using chitosan-nanosilica system in papermaking has been considered in researches recently. In present investigation, confirming the performance of this nanoparticle system in producing paperboard from recycled old corrugated container pulp, the electrostatic performance of chitosan polyelectrolyte in process and product properties has been considered. In this respect, pH of pulp suspension, as one of mains factor affecting the chitosan electrostatic charge, was considered. The results indicated that the process properties (drainage and first pass retention) have been experienced better situation affected by chitosan electrostatic charge in neutral and alkaline conditions. It seems that by changing the pulp suspension pH to neutral and alkaline conditions, the chitosan positive electrostatic charge and its solubility would be decreased and in contrast the fibers negative charge would be increased. This condition would probably affect the chitosan polymer connection and deployment status on fibers surface (loop and tail position) which might perform more effective in floc formation and therefore, drainage and retention increment about 37.5 and 36.5% respectively comparing with control sample and 34 and 7% respectively in comparison with acidic condition. Although the mentioned system has been successful in increasing the mechanical strength comparing the control samples, but the electrostatic charge changes in different pH conditions had less positive impact on these properties (except internal bonding strength).