Structural and Mechanical Properties of Hydrodynamically Activated Wood Pulp in Additive Technologies

One of the techniques of additive technologies is 3D printing. It is a perspective direction in the development of low-rise housing construction. The process of 3D printing can be performed with various materials. Although this study investigates the possibility of applying hydrodynamically activated wood pulp. A fragmentated wood in the process of activation changes physical and chemical properties because of the cavitation effect. Such fragments in the form of the activated pulp are a solid dispersed system, whose properties depend on humidity. The activated pulp mass is created by moisture elimination, and it can be transported through pipelines. The structure is formed in the process of self-adhesion, without any adhesives, by the appearance of autogenous interactions between the wood particles. The obtained material has a sufficiently high strength and water resistance, which are the prerequisites for the use of activated wood pulp in additive technologies. The 3D printed products are constructed by applying some material in layers at certain time intervals. The main requirements are a steady shape and a homogeneity of the structure. Therefore, the limit of creep rate for the pulp mass was determined that is a yield tensile stress point, above which the material (flow) undergoes an intensive plastic deformation. In this study, a conical plastometer was used according to the method of Academician P.A. Rebinder. The measured parameter depends significantly on the humidity of the pulp. There found an inverse relationship between the humidity and the creep limit. The obtained dependence is fundamental for determination of the thickness of applied layers and the time intervals between applications. The homogeneity of the structure in the interlayer section determines the strength of the entire product. It is obtained when the humidity level is greater than 400 % in the contact area. The high humidity level at the contact area with the low average humidity of the material can be created by microwave radiation treatment. Thus, the moisture is distributed across the thickness of the layer. The treatment also increases the humidity level on the surface and reduces it in the center of the material. For citation: Ermolin V.N., Bayandin M.A., Namyatov A.V., Ostryakova V.A. Structural and Mechanical Properties of Hydrodynamically Activated Wood Pulp in Additive Technologies. Lesnoy Zhurnal = Russian Forestry Journal, 2023, no. 2, pp. 121–131. (In Russ.). https://doi.org/10.37482/0536-1036-2023-2-121-131