RESUMO
This research aims to find suitable processing methods that allow the reuse of wood waste to produce wood waste-based engineered wood logs for construction that meet the strength requirements for structural timber for sawn structural softwood. Three types of wood waste were examined: wood packaging waste (W), waste from the construction and furniture industry (PLY), and door manufacturing waste (DW). The wood waste was additionally crushed and sieved, and the granulometric composition and shape of the particles were evaluated. The microstructure of the surface of the wood waste particles was also analysed. A three-component biopolyurethane adhesive was used to bind wood waste particles. An analysis of the contact zones between the particles and biopolyurethane was performed, and the adhesion efficiency of their surfaces was evaluated. Analysis was performed using tensile tests, and the formation of contact zones was analysed with a scanning electron microscope. The wood particles were chemically treated with sodium carbonate, calcium hypochlorite, and peroxide to increase the efficiency of the contact zones between the particles and the biopolyurethane adhesive. Chemical treatment made fillers up to 30% lighter and changed the tensile strength depending on the solution used. The tensile strength of engineered wood prepared from W and treated with sodium carbonate increased from 8331 to 12,702 kPa compared to untreated waste. Additionally, the compressive strength of engineered wood made of untreated and treated wood waste particles was determined to evaluate the influence of the wood particles on the strength characteristics.
RESUMO
In the current study, high-strength boards for the construction industry were developed from renewable natural resources, fibrous hemp shives, and corn starch. During the research, the influence of the composition of the mixture, the processing of raw materials, and technological parameters on the operational properties of the board were evaluated. The influence of the binding material and the water content on the properties of the molded boards was evaluated. It was established that the rational amount of starch is 15% of the mass of the shives, and the amount of water is 10%. It has been established that with the proper selection of the forming parameters of the board, it is possible to avoid internal disintegration of the structure due to the water vapor pressure, increase the bending strength, and ensure uniform sintering of the board throughout the entire volume. It was found that additional processing of hemp shives can increase bending strength by more than 40%. Furthermore, during the processing of shives by chemical means, soluble substances are washed out, which reduces the density and thermal conductivity of the shives. Selection of a rational level of compression allowed us to increase the bending strength of the boards by 40%. The assessment of all factors made it possible to obtain boards with a bending strength of 40 MPa. The additives used made it possible to reduce the water absorption of the boards up to 16 times and obtain non-flammable boards. The thermal conductivity of the resulting boards varied from 0.07 to 0.095 W/(m·K). The analysis of macrostructure and microstructure allowed us to evaluate the process of the formation of bonds between hemp shives.