Study On The Response Mechanism Of Deformation Behavior Of Lignocellulosic Fibers To Their Bonding Properties

In recent years, the demands for environment and sustainable development are put forward more often, and the lignocellulosic fiber material, as a kind of abuntant plant resource, has received wide attention in many fields because of its unique characteristics,such as low density, low cost, recyclablility and biodegradablility. The deformation property of fibers, as a fundamental physical property, influences the application range of wood fiber materials and end-product performace greatly and directly. Therefore, it is very important to study the deformation behavior and the response mechanism of fiber deformmation behavior to inter-fiber bonding properties of lignocellulosic fibers.Firstly, the long fractions of pine TMP fibers were performed with different delignification treatment by sodium chlorite under acid condition, and the fiber materials with different lignin contents and deformation property were obtained. The results showed that with the removal of lignin, the length and width of fiber materials remained unchanged,but the fiber coarseness and water retention value (WRV) were significantly changed. The lignin concentration on the fiber surface decreased as the delignification degree increased.Secondly, the comprehensive evaluation system of different influencing factors for the fiber deformation property was deduced and improved, and the specific equation regarding the effect of different influencing factors on the fiber deformation was obtained. And the response factors, including the parameters of fiber cross-section, the chemical composition of fiber wall and the fiber wall structure (elastic modulus) to the deformation behavior of fibers, were 3.46, 0.26 and 0.06, respectively. Their contributions are to quantify the fiber itself properties on the role of fiber deformation, and further understanding the deformation behavior of wood pulp fibers.Thirdly, the deformation properties of fibers were characterized by different methods,including flexibility of dry and wet fibers, aspect ratio of fiber cross section and collapse index of fibers, and the physical strength of single fiber was measured. The specific development trend during the process of lignin removal was revealed, that is, the physical strength of single fiber decreased and the deformation property increased obviously.Several methods for characterizing the fiber deformation behavior were compared.Finally, the effects of fiber deformation behavior on the micro-bonding properties and macro-physical strength of the fiber network were discussed in details. The response mechanism of fiber deformation to fiber network bonding properties is elucidated. The results shows that the increase of the fiber deformation properties contributed to the increase of inter-fiber relative bonded area (RBA) and shear bond strength (b),and further resulting in the linear increase of the Page bonding strength index with the increase of wet fiber flexibility. The correlation coefficient R2 reached to 0.994. The deformation behavior of lignicellulosic fibers is used to explain the inherent contradiction between macroscopic physical strength and bulk property during the formaiton of fiber network. The contradiction between both properties could be alleviated by adjusting the deformation properties of fiber materials.