Water retention and physical properties of recycled fibers treated with NaOH/urea aqueous solution

摘要

Irreversible hydrogen bonding is the most widely recognized mechanism of fiber homification, and NaOH/urea aqueous solution can break the inter-and intramolecular hydrogen bonds of cellulose. In order to investigate whether or not this solution system reverses the homification of fibers that repeatedly underwent wetting and drying, we studied the degree of homification of repaired libers, which have been treated with NaOH/urea aqueous solution and regenerated in H2SO4/Na2SO4 aqueous solution, and we analyzed the physical properties of the resulting paper sheets. The water retention value (WRV) of the repaired fibers was equivalent to that of virgin pulp, and the homification has been thoroughly reversed. The physical properties of the resulting paper sheets have improved, especially the tear and burst indexes, which have approximately doubled. Moreover, the dissolution/regeneration process slightly inhibited the degree of fiber homification and increased the cycle number of the recycled fibers.