The aim of this study was to assess the effect of the duration of heat treatment on changes in the color, as well as the chemical and mechanical properties of Scots pine sapwood. An important element of the research was to obtain the assumed temperature in the entire volume of samples. Quantitative changes in color and its components were recorded, while mechanical properties were determined in tests of compressive strength parallel and perpendicular to the grain, longitudinal tensile strength and modulus of elasticity and impact strength. The novelty of the research was to determine the above-mentioned parameters for twin samples with identical moisture contents. Chemical analyses were conducted on heat-treated wood that was subjected to heat treatment at 220 °C for a period from 1 to 8 h. Extension of the heat treatment duration resulted in the increasing darkening of the wood, as well as a further reduction in the impact strength and tensile strength parallel to the grain by approx. 40 and 50%, respectively, compared to the control wood, but also compared to heat-treated wood for a shorter treatment duration. The heat treatment of wood caused changes in the contents of the wood components, as well as the elemental composition in the heat-treated wood, compared to the control pine. The changes in the structure of the heat-treated wood were confirmed by the attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR). Observed quantitative changes in the main wood components, its structural changes, as well as wood decomposition and increased crystallinity of cellulose explain significant changes in both the mechanical properties and the color of heat-treated wood.

Objectives The aim of the study was to determine the effect of parameters of the thermal modification process and machining on the size distribution of dust particles of Scots pine (Pinus sylvestris L.) generated during lengthwise milling. Method Unmodified wood and thermally modified wood at temperatures of 130, 160, 190, and 220°C were milled lengthwise at cutting depths of 0.5 and 2 mm. Particle size analysis was done using the sieving method. The content of the finest particles was measured using the laser diffraction method. Results The results indicate that at smaller cutting depths, more smaller particles were formed regardless of the wood modification temperature. Thermal treatment of wood does not cause significant differences in the general particle size distribution of dust. However, the content of the finest dust particles depends on the temperature of wood modification. When machined, wood thermally modified at higher temperatures results in the formation of more dust particles that may pose health risks to employees. This is particularly noticeable at a smaller cutting depth. Conclusion With the increase of the temperature of the modification, the share of the finest dust particles, which are a potential threat to the health of employees, increases. To reduce dust emissions during milling of thermally modified wood, the highest possible cutting depth should be used.

The aim of the conducted experiments was to determine the effect of selected machining parameters on power consumption and surface quality obtained during the milling of beech wood using a computerized numerical control woodworking machine. Surface roughness was tested using the contact roughness measurement method, while roughness parameters Ra and Rz were recorded and cutting energy was determined. Tests were conducted for two variants of cutting speed (7.5 and 15 m·s-1) as well as three variants of chip thickness (0.10, 0.06, and 0.02 mm); additionally, the tests examined different cross-sections of wood. It was found that greater chip thickness and feed speed caused an increase in surface roughness and cutting power. In turn, cutting speed had no effect on surface roughness, whereas its increase resulted in increased cutting power. Surface roughness at the radial and tangential cross-sections was comparable, while it was greater at the transverse cross-section. It was also found that cutting power was lowest at the radial cross-section, while it was greater at the tangential and the greatest at the transverse cross-section.

The aim of this study was to determine the dependencies between mechanical properties of modified wood and its color. Within its scope, quantitative changes in color and chemical composition (mass loss, total carbon content, content of extractives and main components of wood), as well as mechanical properties (compressive strength along the grain, strength and modulus of elasticity in longitudinal tension tests, compression across the grain and impact resistance) of the modified Scots pine sapwood, were determined. Modifications were conducted in the atmosphere of superheated steam (time—4 h, temperature of 130, 160, 190, 220 °C). Thermal modification of wood results in an increase in the modulus of elasticity, a reduction of elasticity, longitudinal tensile strength and compressive strength perpendicular to grain. It was found that color parameters ∆E, ∆L and ∆a are linear functions of the modification temperature. The existence of functional dependencies between mass loss, longitudinal tensile strength, radial modulus of elasticity and parameters of ∆E and ∆L makes it possible to determine these properties of modified wood based on color. In turn, chemical analysis indicated that an increase in the temperature of wood modification caused a decrease of holocellulose and hemicelluloses contents, especially in wood samples modified at 220 °C.