Features of Changing Structural and Morphological Properties of Bamboo Pulp During Refining

Abstract

The wood of tropical plants, including bamboo, has great potential due to its rapid growth, simple cultivation, low cost, and characteristics suitable for the pulp and paper industry. The study considers the structural-morphological properties of unbleached kraft pulp from the wood of Bambusa blumeana, which grows in the Republic of Vietnam. Kraft cooking was carried out on an autoclave system, CAS 420. The obtained bamboo pulp had a yield of 41.7 %, the Kappa number was 17.3. Structural and morphological properties are determined by an automatic fiber analyzer, L&W Fiber Tester. Digital microphotographs were taken with an ImagerM2m Carl Zeiss microscope. Samples were studied before and after refining at the Yokro mill up to 60 °SR. A comparison of the change in the structural and dimensional properties of bamboo pulp fibers was made with industrial softwood and hardwood unbleached pulp. It has been established that, with a general, similar to hardwood and softwood pulp, the nature of the change in properties during refining – a decrease in the average fiber length (from 1.90 up to 1.21 mm), an increase in width (from 17.8 to 20.6 μm), shape factor (from 81.7 to 85.6 %), fines content (from 1.8 to 7.0 %), a decrease in the number of kinks per fiber (from 0,78 to 0,72), the average segment length (from 1.17 to 0.86 mm), also observed for softwood and hardwood pulp, the change in the values of the structural and dimensional characteristics of the fibers in pulp from bamboo occurs to the greatest extent. The reduced fiber width with a high fiber length provides the highest values of the fiber slenderness ratio l/w (from 106.6 for unrefined to 58.8 at 60 °SR) in comparison with softwood (from 81.3 to 60.6) and especially hardwood (from 44.4 to 36.0), which in turn leads to a reduced shape factor and easier damage to the fibers under hydromechanical action during refining, which is expressed in a change in the number of kinks on a fiber. The maximum changes in the structure, size, shape of the fiber and fine content occur already in the first 10 minutes of refining, which indicates the low strength of bamboo fibers and their easy damage. Therefore, it can be assumed that the use of unbleached bamboo pulp in brown paper furnishing will not lead to an increase in its strength. For citation: Khoa H.M., Kazakov Ya.V., Okulova E.O. Features of Changing Structural and Morphological Properties of Bamboo Pulp During Refining. Lesnoy Zhurnal = Russian Forestry Journal, 2023, no. 2, pp. 146–159. (In Russ.). https://doi.org/10.37482/0536-1036-2023-2-146-159