Enzymatic High-Consistency Processing of Softwood and Eucalyptus Kraft Pulps for Textile Fibres

The use of paper grade pulp is an intriguing possibility for broadening the raw material base for regenerated textile fibres. However, the use of kraft pulp requires modification of the molecular weight distribution of cellulose prior to dissolution to ensure good dope quality. Enzymes offer a possibility for selective modification of cellulose and hemicellulose Mw of kraft pulps. Previously, the combined mechano-enzymatic treatment has been shown to allow decreasing enzyme dose and time required for the treatment. Thus, combined mechano-enzymatic pulp processing done at high pulp consistency could be an industrially feasible and environmentally benign way to adjust the molecular weight of kraft pulp prior to dissolution. In this work, the possibilities to adjust the molecular weight of softwood and eucalyptus kraft pulp fibres at high consistency were studied using enzymes capable of hydrolysing cellulose and hemicellulose polymers. Interestingly, with sole endoglucanase, the dose needed for the treatment of eucalyptus kraft pulp treatment was found to be nearly 30-fold higher than for softwood kraft pulp. However, modification of xylan allowed decreasing endoglucanase dose for eucalyptus kraft pulp drastically. Reasons for the different processabilities of softwood and eucalyptus kraft pulps are suggested.