Abstract:

Using Bambusa pervariabilis as the raw materials the effects of acetic acid on the pulp yield, hardness, fiber crystallinity, fiber morphology and paper performance in ethanol pulping were studied. The results showed that the pH value of the solution decreased significantly from 7.3 to 4.1 after 2.0% acetic acid was added. The yield of coarse pulp decreased from 46.64% to 43.14%, which accelerated the degradation of carbohydrates. The Kappa number of pulp decreased from 52.31 to 48.90, which promoted the lignin removal during cooking. The relative molecular weight of lignin increased when the dosage of acetic acid was lower than 6%, while the relative molecular weight of lignin reduced when the dosage of acetic acid was higher than 6%. The addition of acetic acid made the coexistence of lignin degradation or condensation. The average length of the double mass(L_w) decreased from 1.72 to 1.58 mm, and the average width of the doublemass(W_w) decreased from 25.27 to 19.37 μm, which could make the fiber shrink and hard. The loose thickness and tear index of the finished paper were improved after adding acetic acid. The loose thickness increased from 2.16 to 2.30 cm³/g, and the tear index increased from 130.67 to 133.33(mN·m²)/g. The tensile index, flexability and break resistance decreased significantly. The tensile index decreased from 19.06 to 14.37(N·m)/g, the flexability decreased from 6 times to 3 times, and the break index decreased from 1.0 to 0.7 (kPa·m²)/g. The fiber crystallinity decreased from 54.67% to 48.71%. Acetic acid would destroy the fiber crystal zone, and the fiber crystallinity gradually decreased with the increase of acetic acid dosage, while the crystal zones of natural cellulose did not change.

Key words: Bambusa pervariabilis, acetic acid, ethanol pulping, pulp properties