Some Characteristics of China's Papermaking National Conditions and Solutions (2)

Table 2 Triploid poplar and other poplar fiber morphology

(3) From the aspect of fiber morphology, triploid Populus tomentosa is superior to common Populus tomentosa, Populus nigra, and Beijing 605 Yang. Triploid P. tomentosa fibres average 1.28 mm in length. This length is rare in 5-year-old poplar species. They are uniformly distributed, have a large aspect ratio and a small wall-to-wall ratio, and are of the thin-walled cell type with a good fiber morphology. It is very advantageous for pulping yield, paper strength, and papermaking interlacing force and softness (see Table 2).
(4) From the viewpoint of pulping energy consumption and whiteness of pulp: The wood density of Triploid Chinese White Poplar (0.4 t/m3) is moderate, and the fiber lines are straight and there is no black heartwood, which is superior to black poplar which often has black heartwood. At the same beating degree (eg 70°SR), the energy consumption of the triploid Chinese white poplar was 1240 kWh/t, about 14% lower than that of white poplar (1420 kWh/t), and 21% lower than that of black poplar (1580 kWh/t). Therefore, it is a low-energy tree species. Triploid Chinese white poplar wood has 53% whiteness, no black heart, low bleaching and consumption, and low pollution. Under the APMP process, the whiteness of the pulp is 80% under the application of 3% hydrogen peroxide; and the amount of hydrogen peroxide used in the black poplar At 5%, the whiteness of the pulp reached 75%. It can be seen that the triploid Chinese white poplar has a 40% saving in energy consumption compared to black poplar.
(5) From the viewpoint of the quality of beating and papermaking, the tensile strength and tear strength of paper are important indicators of the quality of paper. In general, the stronger the binding capacity between the pulp fibers, the better the tensile strength; and the tear strength is related to the fiber length in addition to the fiber bond strength. In APMP pulping, under the same beating degree (eg 70°SR), the tensile index of triploid Populus tomentosa is 42N·m/g, that of Populus tomentosa is 37.5N·m/g, and that of Black Poplar is 30.0N·. m/g indicates that the paper strength of triploid Chinese white poplar is 14% higher than that of ordinary white poplar and 42% higher than that of black poplar. From the tear index, at 70°SR, the triploid Populus tomentosa was 4.8 mN·m2/g, the common Populus tomentosa was 4.3 mN·m2/g, and the black poplar was 4.0 mN·m2/g, which was far more common than normal. White Poplar is 11.6% better than Black Poplar 20%. Therefore, regardless of the paper's tensile index and tear index, triploid Chinese white poplar is better than blue-green poplar than green-blue, better than ordinary white poplar, compared to black poplar is even better. (Professor of the Chinese Academy of Engineering, Beijing Forestry University, Zhu Zhiyu)