The effect of pulping on fiber

The effect of beating on the fibers is mainly to cause physical and chemical changes. No matter which type of beating equipment is used, the fibers are cut, crushed, absorbed and swollen, and the fibers are refined. When the fiber is subjected to the above-mentioned effects, its major changes occur on the cell wall of the fiber. The changes of the fiber cell wall are as follows:
(1) The reason why beating pulp causes the displacement and deformation of the cell wall of the fiber to cause displacement and deformation of the cell wall is that the fiber undergoes a mechanical force in the beating process and causes the microfibers in the middle layer of the secondary wall to bend and deform so that the microfibers are The increase in interstices creates conditions for the fibers to absorb more moisture. The fiber becomes flexible after absorbing water and deforms, and plays an important role in removing the primary wall and the outer layer of the secondary wall.
(2) Beating the fiber to break the primary and secondary walls The fibers that have not been removed from the primary wall appear smooth, stiff, and difficult to absorb and swell. Therefore, the mechanical force of the pulping equipment and the mutual friction between the fibers must be used. The outer wall of the primary and secondary walls is broken, so that the fine fibers of the middle wall of the secondary wall are separated to achieve the purpose of full swelling and fibrillation of the fibers. Under normal circumstances, the difficulty of removing the primary wall and the secondary wall outer layer of different types of fiber raw materials is also not the same, so the degree of difficulty in fibrillation during beating is also not the same, such as the removal of pulp from wood pulp. To be difficult, the removal of sulphate wood pulp and sulphate wood pulp is difficult.
(3) Absorption of pulp fiber after beating The swelling and swelling of the fiber is slow before the primary wall of the intumescent fiber is broken. After the beating treatment, the primary and secondary walls of the fiber are continuously broken and the fiber is increased. The swelling of water absorption makes the fiber become soft and plastic, the external surface area increases, the internal structure is relaxed, and the cohesion between molecules decreases, which is favorable for the progress of fibrillation. Due to the presence of amorphous regions and a large number of hydroxyl groups in the cellulose and non-cellulose molecular structures, polar attraction occurs with water molecules, and water molecules enter amorphous regions, increasing the distance between cellulose molecules and increasing the surface area of ​​fibers. Large, causing swelling and swelling.
(4) After the physical (mechanical) action of the pulping equipment, the fibrillated pulp fibres of the fibres are subjected to mechanical action of beating in the beating process to produce longitudinal splits, the fine fibres are separated on the surface, and the fluffing of both ends of the fibres occurs. Called fine fibrosis. Due to the occurrence of fibrillation, the interweaving ability between the fibers and the fibers is enhanced, so that the physical strength of the paper products is greatly improved.
(5) The fibers are cut transversely due to the shearing action of the beating device. During the beating process, the fibers are cut due to the shearing action of the pulping apparatus. At the same time, in the case of high beating pressure and high concentration, the mutual friction between the fibers can also cause the transverse cut of the fibers. Long cut fibers can be appropriately cut to improve the uniformity and smoothness of the paper molded articles. However, when cut too short, the strength of paper products will be reduced. In the usual case, the cut off of the fibers is related to the degree of swelling. Under the same beating condition, the water swelling and swelling are good, and the fiber has good softness and plasticity, and it is not easy to be cut, and it is easy to split the silk. Conversely, water swelling is not good and fibers are hard and they are easily cut.
(6) The relationship between the properties and strength of beating and paper products The quality of beating directly affects the strength of paper products and the binding force of fibers. A good beating quality can produce higher strength paper products. If the strength of the paper-based molded article is not enough, it cannot be simply attributed to the fact that the strength of the single fiber is insufficient, and it should be considered whether the fiber-binding force is insufficient. The strength of a paper moulding product is determined by various reasons. It depends on the mutual binding ability between the fibres, the length of the fibres, the strength of the fibres themselves, the condition of the fibre surface and the arrangement of the fibres. In short, the strength of paper molded products is mainly derived from the binding force of fibers, which is determined by the degree of hydrogen bonding.
As the beating continues, on the one hand, the binding force of the fibers is increased, while on the other hand the average length of the fibers is shortened. This is a pair of contradictions in the process of beating. If you want to increase the strength of paper products, you have to increase the length of the paper products. The increase in crack length depends on the growth of fiber binding strength. The increase in fiber binding force depends on the growth of the specific surface area of ​​the fibers, depending on the size of the paper. Beating degree.
If you want to increase the endurance of paper molded products, you generally want to use lighter pulp; if you want to increase the bursting resistance, you generally want to increase the binding force of the fiber, increase the chance of hydrogen bonding, and increase the strength of the fiber itself. Intertwined ability. In short, different pulping methods can be used to process paper molding products with different requirements.