The effects of heating without water removal and drying on the swelling as measured by water retention value and degradation as measured by intrinsic viscosity of cellulose papermaking fibers

The effects of heating without water removal and drying of bleached kraft fibers were separately investigated. Water swellability as measured using a water retention value method (WRV) and cellulose degree of polymerization as measured using a viscosity method were used to gage the effects of such treatments on fibers. The drying of fibers at temperatures above 100°C resulted in significant decreases in WRV, as expected. However, heating fibers without water removal at the same temperatures resulted in a decrease in WRV much less than caused by drying. Drying at high temperatures reduced the cellulose viscosity only slightly, whereas heat treatment without water removal at high temperatures resulted in much greater losses in cellulose viscosity. The results of this study indicate that the time-temperature-humidity history of a fiber during papermaking and paper recycling can produce fibers with very different papermaking qualities.