Effects of heat treatment on the chemical compositions and thermal decomposition kinetics of Japanese cedar and beech wood

Chemical Composition and Mechanical Properties of Wood after Thermal Modification in Closed Process under Pressure in Nitrogen

In this study, silver birch (Betula pendula) and Scots pine (Pinus sylvestris) wood planks (1000 × 100 × 25 mm) were thermally modified in pilot-scale equipment. Research extended our knowledge of the thermal modification (TM) process in a closed system under nitrogen pressure, as well as how process parameters affect the chemical composition and mechanical strength of wood. Various TM regimes were selected-maximum temperature (150-180 °C), modification time (30-180 min), and initial nitrogen pressure (3-6 bar). Chemical analyses were performed to assess the amount of extractives, lignin, polysaccharides and acetyl group content following the TM process. The mechanical properties of TM wood were characterized using the modulus of rupture (MOR), modulus of elasticity (MOE), and Brinell hardness. The MOR of both studied wood species following TM in nitrogen was reduced, but MOE changes were insignificant. The Brinell hardness of TM birch wood's tangential surface was much higher than that of the radial surface, although Scots pine wood showed the opposite pattern. TM birch and pine wood specimens with the highest mass loss, acetone soluble extractive amount, and the lowest xylan and acetyl group content had the lowest MOR and Brinell hardness.

Properties of Heat-Treated Wood Fiber-Polylactic Acid Composite Filaments and 3D-Printed Parts Using Fused Filament Fabrication

Wood fibers (WFs) were treated at a fixed heat temperature (180 °C) for 2-6 h and added to a polylactic acid (PLA) matrix to produce wood-PLA composite (WPC) filaments. Additionally, the effects of the heat-treated WFs on the physicomechanical properties and impact strength of the WPC filaments and 3D-printed WPC parts using fused filament fabrication (FFF) were examined. The results revealed that heat-treated WFs caused an increase in crystallinity and a significant reduction in the number of pores on the failure cross section of the WPC filament, resulting in a higher tensile modulus and lower elongation at break. Additionally, the printed WPC parts with heat-treated WFs had higher tensile strength and lower water absorption compared to untreated WPC parts. However, most of the mechanical properties and impact strength of 3D-printed WPC parts were not significantly influenced by adding heat-treated WFs. As described above, at the fixed fiber addition amount, adding heat-treated WFs improved the dimensional stability of the WPC parts and it enabled a high retention ratio of mechanical properties and impact strength of the WPC parts.

Three-dimensional porous wood monolithic columns for efficient purification of spike glycoprotein of SARS-CoV-2

Considerable research has been devoted to finding a cost-effective chromatographic matrix with efficient adsorption and high throughput. Wood exhibits complex micro-network structures that make it a powerful contender for a novel environment-friendly chromatographic matrix material. We demonstrate a novel strategy to manufacture a wood monolithic column, which chemically modified the wood and imported diethyl aminoethyl, diethylamine, and amino groups. This wood monolithic column can maintain fully monolithic column performances and highly selective to spike glycoprotein of SARS-CoV-2 by ion exchange force. The wood monolithic column was evaluated by static adsorption, dynamic adsorption, and frontal analysis. The results showed that the static adsorption capacity of the wood monolithic column with 2-diethylaminoethylchloride hydrochloride for bovine serum albumin was 14.72 mg/g, and the adsorption process was chemisorption. In addition, it retained 80 % adsorption capacity after 110 repeated adsorption-elution cycles.

Furanic Polymerization Causes the Change, Conservation and Recovery of Thermally-Treated Wood Hydrophobicity before and after Moist Conditions Exposure

The Whilhelmy method of contact angle, wood thermal properties (TG/DTG), infrared spectroscopy, etc. was used to define the hydrophobicity of heat-treated beech and fir wood at increasing temperatures between 120 °C and 300 °C. By exposure to wet conditions during 1 week, the hydrophobic character obtained by the heat treatment remains constant heat-treated. Heat induced wood hydrophobation, was shown by CP MAS ¹³C NMR and MALDI ToF mass spectrometry to be mainly caused by furanic moieties produced from heat-induced hemicelluloses degradation. This is caused by the acid environment generated by the hydrolysis of the hemicelluloses acetyl groups. Furfural polymerizes to linear and branched oligomers and finally to water repellent, insoluble furanic resins. The water repellent, black colored, cross-linked polymerized furanic network is present throughout the heat-treated wood. Wood darkening as well as its water repellency due to increasing proportions of black colored furanic resins increase as a function of the increase with treating temperature, becoming particularly evident in the 200 to 300 °C treating temperature range.

Characterization and Prediction of Mechanical and Chemical Properties of Luanta Fir Wood with Vacuum Hydrothermal Treatment

Since the chemical composition of wood is closely related to its mechanical properties, chemical analysis techniques such as near-infrared (NIR) spectroscopy provide a reasonable non-destructive method for predicting wood strength. In this study, we used NIR spectra with principal component analysis (PCA) to reveal that vacuum hydrothermal (VH) treatment causes degradation of hemicellulose as well as the amorphous region of cellulose, resulting in lower hydroxyl and acetyl group content. These processes increase the crystallinity of the luanta fir wood (Cunninghamia konishii Hayata), which, in turn, effectively increases its compressive strength (σc,max), hardness, and modulus of elasticity (MOE). The PCA results also revealed that the primary factors affecting these properties are the hemicellulose content, hydroxyl groups in the cellulose amorphous region, the wood moisture content, and the relative lignin content. Moreover, the ratios of performance deviation (RPDs) for the σc,max, shear strength (σs,max), hardness, and modulus of rupture (MOR) models were 1.49, 1.24, 1.13, and 2.39, indicating that these models can be used for wood grading (1.0 < RPD < 2.5). Accordingly, NIR can serve as a useful tool for predicting the mechanical properties of VH-treated wood.

Isothermal Kinetic Analysis of the Thermal Decomposition of Wood Chips from an Apple Tree

The thermal decomposition of wood chips from an apple tree is studied in a static air atmosphere under isothermal conditions. Based on the thermogravimetric analysis, the values of the apparent activation energy and pre-exponential factor are 34 ± 3 kJ mol−1 and 391 ± 2 min−1, respectively. These results have also shown that this process can be described by the rate of the first-order chemical reaction. This reaction model is valid only for a temperature range of 250–290 °C, mainly due to the lignin decomposition. The obtained results are used for kinetic prediction, which is compared with the measurement. The results show that the reaction is slower at higher values of degree of conversion, which is caused by the influence of the experimental condition. Nevertheless, the obtained kinetic parameters could be used for the optimization of the combustion process of wood chips in small-scale biomass boilers.

Effects of One-Step Hot Oil Treatment on the Physical, Mechanical, and Surface Properties of Bamboo Scrimber

Bamboo scrimber is a new type of bamboo-based panel that is prone to be affected by biological and service environments under outdoor conditions. In this paper, the physical and mechanical performance and the microchemical and surface properties of untreated and hot-oil-treated bamboo scrimber were analyzed to illustrate the processing mechanism of scrimber. Methyl silicone oil treatment was carried out at 120, 140, and 160 °C for 2, 4, and 6 h. The density, mechanical properties, air-dried moisture content, surface morphology, chemical structure, swelling properties, color, and contact angle of the bamboo scrimber were analyzed to evaluate the treatment effectiveness. Observation of the environmental-scanning electron microscope indicated that the glue layer of the bamboo scrimber was not significantly damaged after hot oil treatment. At low temperatures, the mechanical properties did not change significantly. Infrared-spectrum analysis showed a significant decrease in mechanical properties at higher temperatures and longer treatment time for the degradation of hemicellulose. The contact angle test and swelling properties test showed that the hot oil treatment improved the dimensional stability and reduced the wettability on the surface of the bamboo scrimber. The above analysis results show that the treatment at 140 °C for 2 h is most effective.

Surface Structural Transformation of Pre-carbonized Solid Biomass from Japanese Cedar via ATR-FTIR and PCA

This present research applied the ATR-FTIR technique and principle component analysis (PCA) to investigate molecular surface changes in pre-carbonized solid biomass, called Kindai Bio-coke (BIC) and Japanese cedar. The product is utilized as an alternative to coal coke in the cupola furnace in the steel industry in order to reduce CO₂ emissions. The aim is to explore key elements for improving the BIC product applications from the fundamental molecular scale by using PCA to distinguish between changes during the BIC transformation and the differences in BIC samples. Results revealed that transformation occurred at the surface of Japanese cedar raw materials and Japanese cedar BIC. Major changes were observed in the O-H, C-H and C-O stretching regions. The intensity of the IR bands attributed to aliphatic methyl (CH₃) and methylene (CH₂) stretching modes increased, while a weak O-H stretching intensity associated with BIC hydrophobic characteristic decreased.