Wood modification with bio-based chemicals such as sorbitol–citric acid (SorCA) system is a low-cost and effective approach, while the low pH of the modifying agent reduces the mechanical properties of modified wood. Thus, this study was conducted to find alternative polycarboxylic acids with comparable functional groups, reactivity, and processing conditions. Silver beech wood (Betula pendula Roth.) was modified through in situ esterification approach using sorbitol in combination with citric acid (CA), tartaric acid (TA) or malic acid (MA). Wood samples were modified at 20% w/w of sorbitol–CA, –TA, and –MA at 1:3 molar ratio and cured at 140°C for 24 h. The SorCA modified samples showed the highest leaching resistance followed by SorMA and SorTA. The samples modified with SorTA and SorMA illustrated superior dimensional stability compared with SorCA. The modulus of elasticity (MOE) was slightly improved in all modified samples in comparison with unmodified birch. However, the modulus of rupture (MOR) was marginally decreased, particularly in the samples modified with SorCA and SorTA.

This study unravelled the intricacy of bio-based hydrophobic formulae as a substitute for the conventional emulsified paraffin wax (hydrowax), a hydrophobic additive currently utilised in high-density fibreboard (HDF) fabrication. Utilisation of hydrowax is not a sustainable practice due to the potential depletion of its fossil-based sources. The industrial acceptability of a renewable hydrophobic additive depends on several stages of trials. Therefore, through a pilot-scale trial, this study explored the substitution effect of bio-based tall oil distillation product (TODP) in the HDF panels, establishing its mechanical and water-related properties. While the mechanical properties of the panels were not primarily influenced by the TODP-based formula, the water-related properties of the HDF panels produced with 1% TODP were significantly better than the control panels. Additionally, the TODP exhibits superior mechanical and hydrophobic properties compared to the panels made with hydrowax. The ANOVA results further corroborate that TODP 1 at a 1% inclusion rate is the most significant formula. The types and concentrations of TODP are key factors influencing the performance of bio-based hydrophobic additives in HDF panels. Therefore, the present research supports the development of a sustainable hydrophobic bio-additive by determining the water-resistance and mechanical properties of TODP in HDF production.

This study investigates the mechanical and physical properties of a wood-based polymer composite DuraSense® 3D S50 Flex K to enhance its potential in large-scale additive manufacturing by studying the influence of printing orientation on the mechanical characteristics of the product. To assess performance, the specimens were produced with different printing layer orientations: at 0°, 30°, 45°, and 90° to the sample length, which corresponds to load application during the tests. Tensile strength, flexural strength, modulus of elasticity, hardness, water absorption, thermophysical properties and microstructure were determined for the samples. The 0° specimens exhibited the highest tensile (15.39 MPa) and flexural strength (26.05 MPa), while the 90° orientation specimens showed reductions in strength of 72% and 69%, respectively. The modulus of elasticity also decreased by 71% at 90°, confirming anisotropy. Additional tests revealed a Brinell hardness of 179.9 N/mm2, a water absorption of 19.75%, with minimal dimensional change, and a thermal conductivity of 0.1553 W/m·K. Microscopic analysis showed porosity and uneven fibre distribution, indicating the need for composite optimisation. These findings confirm the importance of orientation-aware design in large-scale additive manufacturing and provide the background for future work focusing on the development of printing strategies and computational modelling to enhance print quality, interlayer adhesion, and performance in applications.

The global requirement to mitigate environmental challenges demands a paradigm shift towards sustainable materials. Forest-based products, primarily derived from wood, present a promising path due to their abundance and renewability. However, enhancing their properties to meet modern demands remains a challenge. This review article, the first of its kind, explores the transformative potential of incorporating graphene and graphene-based nanomaterials into forest-based products to overcome the challenges associated with mass-scale applications. Graphene, a two-dimensional carbon nanomaterial, has emerged as a multifunctional additive with exceptional mechanical, electrical, and thermal properties. Functionalization of graphene through covalent or non-covalent modifications has emerged as a key strategy to tune its characteristics and expand its utility across different domains. Recent studies highlight its promising role in forest-derived products, including coatings, composites, adhesives, and lignocellulosic substrates. Graphene and its derivatives, such as graphene oxide, reduced graphene oxide, and graphene nanoplatelets, have been shown to enhance barrier properties, mechanical strength, fire retardancy, and environmental resistance, while also reducing volatile organic compound emissions through formaldehyde scavenging. Moreover, graphene-coated forest-derived substrates demonstrate potential for applications in energy storage, smart sensors, and multifunctional green devices. This review compiles recent advances in integrating graphene with wood and lignocellulosic materials to address the urgency and potential of this innovative approach towards a more sustainable future. It also discusses the practical challenges in applying graphene, thereby providing a comprehensive perspective for its future research and industrial applications.

The increasing interest in sustainable and bio-based wood modification strategies has led to growing attention toward improving the performance of low-durability wood species for exterior applications. Sorbitol-citric acid(SorCA) modification has previously been reported as an effective approach for improving wood properties. However, despite these studies, the biological durability of SorCA-modified silver birch (Betula pendula), particularly its resistance to mold and fungal decay, has not been systematically investigated. Moreover, its performance under natural outdoor exposure conditions remains largely unexplored. Thus, this study evaluates the decay and outdoor weathering resistance of birch wood modified with a SorCA system. Birch wood samples were vacuum-pressure impregnated with aqueous solutions of SorCA at 20% and 40% w/w and cured at 140 °C. The distribution of the modifying agent within the wood structure was examined using X-raymicrotomography, which confirmed effective penetration with partial or complete filling of the wood lumina by the in-situ formed polyester network. The modified samples were subjected to ten months of natural weathering, mold exposure under high humidity conditions, and also to white-rot fungi (Trametes versicolor). Outdoor weathering results indicated improved resistance to surface deterioration in modified wood, although increased color change (ΔE) was observed due to the formation of chromophoric groups during curing and subsequent photodegradation. Under the conditions investigated, SorCA modification enhanced biological durability and weathering resistance, especially at higher concentrations. In general, SorCA modification showed great potential to improve the durability of birch wood with enhancing biological durability and weathering resistance.

In this research, the wood-based polymer composite DuraSense® 3D S51 Flex K, composed of 50% wood fibers and 50% polymer, was studied for the manufacture of products using large-scale additive manufacturing technology. Experimental specimens were produced to determine composite properties and the influence of printing strategy on these properties. The study involved creating test samples in four different printing orientations relative to the horizontal axis: 0°, 30°, 45°, and 90°, that is using different printing strategies, which affected the mechanical properties of the products. All sample types were tested for density, tensile strength, flexural strength, and underwent microscopic investigation. The test results demonstrated sufficient mechanical properties and durability of the obtained products, and enabled evaluation of the relationship between printing strategy and the strength characteristics of the products. It was found that the mechanical properties of products obtained by 3D printing are lower than those of the raw materials (granulate for additive manufacturing) as declared by the manufacturer. This is explained by structural changes, specifically the formation of micropores and the reduction of interlayer bonds during large-scale additive manufacturing. Considering the determined strength and durability indicators, as well as the advantages of additive manufacturing technology, the use of wood-based polymer composites is recommended for the production of various products using 3D printing.

This study was conducted to evaluate the physical and chemical properties of Scots pine (Pinus sylvestris L.) sapwood modified with tannin-based formulas. Wood samples were pressure impregnated with tannin solution at five different concentrations of citric acid (0, 2, 10, 20, and 40 wt/wt%). The tannin-modified samples were analyzed by mean of their weight percentage gain (WPG), leaching resistance (LR), bulking coefficient (BC), anti-swelling efficiency (ASE), Fourier-Transform Infrared (FTIR) spectroscopy, and optical microscopy, and the results were compared with unmodified sapwood and heartwood samples. It is observed that the WPG and dimensional stability of the samples increased with increasing the citric acid (CA) concentrations and the highest WPG was attained (44%) with a formulation containing 20% CA while, the BC, LR, and ASE values were considerably higher in the samples modified with 40% CA concentration as compared to other modification formulas and also the unmodified sapwood and heartwood samples. FTIR spectroscopy analyses showed higher esterification degree with higher concentrations of CA. Overall, this study suggests the potential of a fully bio-based tannin formula to improve the water-related properties of Scots pine sapwood.

Wood modification is essential to enhance the performance and longevity of wood as a material while maintaining its natural and sustainable characteristics. By modifying wood, its properties can be significantly improved without the need for toxic preservatives. Thus bio-based wood modification is vital for enhancing wood properties sustainably, reducing environmental impact, and meeting the demand for eco-friendly, non-toxic, and renewable material solutions. In this study, bio-based formulae were used on pine sapwood for enhanced decay and weathering resistance. Quebracho tannin solutions (20 %) with different concentrations of citric acid (CA) as a cross-linker were prepared and then vacuum-pressure impregnated in Scots pine sapwood before curing them at 140 °C. The durability performance of untreated and tannin-impregnated wood samples was assessed against accelerated weathering, mould growth and brown rot decay fungus Coniophora puteana (Schumach.) P. Karst. Experimental results showed that the weathering resistance was apparently improved by tannin modification with higher levels of CA, as reflected by color stability, crack formation and contact angle. While tannin modification increased mould susceptibility, the decay resistance was notably enhanced in all modified wood samples. The acidity of the formulas at high CA levels may increase the risks of hydrolytic degradation of wood, and thus, low CA concentrations (e.g. 2 %) appear optimal for balancing performance and chemical stability. These findings underscore the potential of 100 % bio-based tannin–CA systems to enhance wood durability, offering a promising pathway for sustainable wood protection strategies.