Wet strength development in sisal cellulose fibers by effect of a laccase–TEMPO treatment

The aim of this study was to investigate the oxidation of sisal pulp fibers by laccase–TEMPO system which had never previously been examined. High cellulose content sisal fibers were treated with laccase from Trametes villosa and a varying amount of TEMPO in order to evaluate the potential of laccase–TEMPO system to improve the paper physical properties of pulp fibers. The effect of the oxidative treatment on the carboxyl group content and viscosity of pulp fibers was examined. The resulting papers were analyzed in terms of strength-related properties, water absorbency capabilities and fiber morphology. Oxidation of sisal pulp by laccase–TEMPO system resulted in a very important improvement of wet strength of the resulting papers, suggesting the formation of a substantial amount of aldehyde groups in cellulose chains providing interfiber bonding through hemiacetal linkages.