INFLUENCE OF TEMPO-MEDIATED OXIDATION ON THERMOMECHANICAL PULP

To enhance the poor inter-fiber bonding potential of TMP long fibers, a large amount of carboxylic groups were introduced to TMP long fibers by TEMPO-mediated oxidation with high selectivity. The amounts of introduced carboxylic groups were close related to the NaClO charge. Both the curl and kink index of oxidized TMP long fibers declined significantly, which made the fibers more flexible. The lignin was dissolved during TEMPO-mediated oxidation, and the lignin content was 24.2% as the carboxylic content was 1444 mmol/kg, in contrast to the untreated one, represented 33.6%. TEMPO-mediated oxidation led to the significant drop of uncondensed lignin and beta-O-4 lignin content as well. The generation of carboxylic groups enhanced both the tensile and burst strength of oxidized TMP significantly, 70% higher than the untreated one as the carboxylic content was 1444 mmol/kg. Unfortunately, the side reactions during TEMPO-mediated oxidation resulted in the decline of fiber intrinsic strength, which should be lead to the drop of paper tear strength.