Лесной журнал (Oct 2024)
Structural Boards Made of Hydrodynamically Activated Pine (Pinus sylvestris) Bark without Binders
Abstract
Bark is a large-tonnage waste in a number of wood processing technologies requiring efficient use. One of the promising areas of bark use is the production of boards without synthetic binders. Research has been conducted on the production of structural boards from Pinus sylvestris bark without a binder. The method is based on preliminary hydrodynamic activation of bark. The initial bark undergoes primary crushing in a hammer mill. After that, it is mixed with water at a concentration of 6 %. Then the resulting mass is activated in a rotary pulsation disperser, a carpet is formed from it, cold pressing is carried out, and then hot pressing. As a criterion for assessing the degree of mass activation, water-retaining capacity is adopted. The dependencies have been determined between the duration of treatment and water-retaining capacity, as well as the strength of the boards and water-retaining capacity. The latter made it possible to obtain the optimal value of the water-retaining capacity equal to 290 %. A multifactorial experiment has been conducted to develop the optimal hot pressing mode. As a result, the optimal mode for pressing the boards has been determined: temperature – 190 °C; specific process duration – 2.8 min/mm; pressing pressure – 4.4 MPa. The properties of the boards produced in this mode are: density – 980 kg/m 3 ; bending strength – 24 MPa; swelling during soaking for 24 hours – 5 %; water absorption – 9 %. After soaking and subsequent drying to a moisture content of 5 %, the boards retain 75 % of their before soaking. In this case, the geometric dimensions return to the original ones. The resulting boards can be used as a sheet finishing and structural material, in house-building (as a base for floor and roofing materials), in furniture production, especially in severe temperature and humidity conditions. The conducted research shows the possibility of producing board materials with high performance properties from pine bark without binders.
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