The potential of ammonium lignosulfonate (ALS) as an eco-friendly additive to urea–formaldehyde (UF) resin for manufacturing high-density fiberboard (HDF) panels with acceptable properties and low free formaldehyde emission was investigated in this work. The HDF panels were manufactured in the laboratory with very low UF resin content (4%) and ALS addition levels varying from 4% to 8% based on the mass of the dry wood fibers. The press factor applied was 15 s·mm−1. The physical properties (water absorption and thickness swelling), mechanical properties (bending strength, modulus of elasticity, and internal bond strength), and free formaldehyde emission were evaluated in accordance with the European standards. In general, the developed HDF panels exhibited acceptable physical and mechanical properties, fulfilling the standard requirements for HDF panels for use in load-bearing applications. Markedly, the laboratory-produced panels had low free formaldehyde emission ranging from 2.0 to 1.4 mg/100 g, thus fulfilling the requirements of the E0 and super E0 emission grades and confirming the positive effect of ALS as a formaldehyde scavenger. The thermal analyses performed, i.e., differential scanning calorimetry (DSC), thermal gravimetric analysis (TGA), and derivative thermogravimetry (DTG), also confirmed the main findings of the research. It was concluded that ALS as a bio-based, formaldehyde-free adhesive can be efficiently utilized as an eco-friendly additive to UF adhesive formulations for manufacturing wood-based panels under industrial conditions.

• A methodology has been suggested for mathematical modeling and research of two mutually connected problems: the temperature distribution along the thickness of fl at wood details subjected to unilateral heating and the energy consumption of this process. For the realization of the methodology, a 1-dimensional mathemati

A numerical approach for the computation of the specific (for 1 m2) energy consumption, qe, and the specific heat flux, dqe/dτ, needed for covering of the emission in the surrounding environment of the subjected to unilateral heating flat wood details aimed at their plasticizing and following bending has been suggested. The approach is based on the integration and differentiation of the solutions of a linear model for the calculation of the non-stationary 1D temperature distribution along the thickness of subjected to unilateral heating flat wood details, suggested by the authors earlier.For the numerical solution of the model aimed at the determination of qe and dqe/dτ software program has been prepared, which was input in the calculation environment of Visual Fortran. Using the program, computations have been carried out for the determination of the change in the energy qe and in the flux dqe/dτ, which are consumed by spruce details with an initial temperature of 20 °C, moisture content of 0.15 kg·kg-1, and thicknesses of 6 mm, 8 mm, and 10 mm during their 10 min unilateral heating at temperatures of the heating metal band of 100 °C, 120 °C, and 140 °C and of the surrounding air of 20 °C. The obtained results are graphically presented and analyzed.

A mathematical model and a numerical approach for the computation of the specific energy consumption, which is needed for warming up of flat furniture elements before their lacquering, have been suggested. The approach is based on the integration of the solutions of a non-linear model for the calculation of the nonstationary 1D temperature distribution along the thickness of subjected to unilateral convective heating furniture elements. With the help of a self-prepared software program, computations have been carried out for the determination of the change in the specific energy, which is consumed by oak furniture elements with an initial temperature of 20 °C, moisture content of 8 %, thickness of 16 mm, and length of 0.6 m, 1.2 m, and 1.8 m, during their 10 min unilateral convective heating by hot air with temperature of 100 °C and velocity of 5 m·s−1.