THE INFLUENCE OF THE CONDITIONS IN KRAFT COOKING OFLOBLOLLY PINE ON FIBER CHARGE

摘要

Laboratory kraft cooking of loblolly pine was carried out to investigate the effect of cooking conditions; including: EA, sulfidity, and cooking temperature, on fiber charge. Conductomeric titration method was applied to determine the carboxylic acid group content of bulk fibers. Polyelectrolyte adsorption method was used to measure surface charge on bulk fibers. The results show that when cooking to the same H-factor, low EA charge, and low cooking temperature are favorable for increasing bulk and surface charge of fibers. Sulfidity did not have a significant effect on bulk and surface carboxylic acid group content except under low EA (12%) conditions, in which higher sulfidity leads to lower carboxylic acid group content and higher surface charge of bulk fibers. Depending on the level of lignin content, carboxylic acid group content in lignin accounts for approximately 14-44% of the carboxylic acid group content on bulk fibers.