Measurement of Delignification Diversity within Kraft Pulping Processes, 1995 Pulping Conference Proceedings

Brian Boyer & Alan Rudie

IPST

Measurements of the variation in kraft pulp lignin content have been the subject of intense interest for several years. Historically, macroscale variation has been determined in mill studies using hanging-baskets within batch digesters; at which time, lignin content variability was observed and related to chip location and thickness. On a smaller scale, slices of cooked chips have been examined to determine lignin content variability. Unfortunately, few data are available on lignin content variability within and between individual fibers. Available data do suggest, however, that a high level of interfiber delignification diversity should be present. This study has measured lignin content variability within and between individual kraft softwood pulp fibers using two laboratory methods: density gradient column distributions and single-fiber FTIR microspectroscopy. Large variations in fiber-to-fiber lignin content were observed in a 17.6 kappa number pulp, a 78.0 kappa number pulp, and a 21.8 kappa number mill-produced pulp.