Enhancing Douglas-fir pulp properties with a combination of enzyme treatments and fiber fractionation

A softwood kraft pulp derived primarily from Douglas-fir was used in experi ments with enzymes to improve strength properties. Industrial-scale fiber f ractionation was combined with a cellulose treatment of the long fiber frac tion. Handsheet properties were evaluated after the long fiber fraction had been recombined with the untreated short fiber fraction. Density and smoot hness were improved in handsheets derived from the unrefined pulps. Both th e tensile index and burst index were increased by about 15% over their corr esponding controls. Similar handsheet modifications could be achieved at lo wer enzyme dosages when the pulp was subjected to refining after the treate d fibers were recombined with the untreated fibers.