Enhancement of Pulp Strength by Forming Polyelectrolyte Multilayers on APMP Fibers

Abstract

The layer-by-layer deposition technique was adopted in this paper to improve the physical strength properties of alkaline peroxide mechanical pulp (APMP). The cationic starch (CS), anionic polyacryamide (APAM) and cationic polyacryamide (CPAM) were chosen and used to build-up polyelectrolyte multilayers on surface of APMP fibers. The improvements of physical strength of pulp through adsorption of different polyelectrolyte onto fibers were discussed and compared. The results showed that when the APMP fibers were treated with CPAM, the breaking length and burst index were 53% and 83% respectively, higher than that of untreated pulp. The optimal treatment conditions are 60 mgCPAM/g pulp, 1.5% pulp concentration and 9min treatment time. The pulp deposited by CPAM-APAM polyelectrolyte multilayer gave a highest physical strength compared with pulp with other multilayer deposition such as CS-APAM. At the whole beating degree range investigated in this paper, the CPAM-APAM deposition on fiber surface can improve the physical strength properties significantly, especially when the beating degree is at 40oSR. In addition, the improvement of physical strength can be remained even after pulp refining.