Norway spruce was impregnated with a eutectic mixture of capric acid and stearic acid. The binary fatty acid was used as a bio-based phase-change material (PCM) for further applications with wood as a latent heat-storage material in building components. For this purpose, different concentrations of impregnation were evaluated. The weight-percentage gain of 124% was the highest for the pure fatty acid mixture, and the PCM-impregnated wood increased density from 470 kg/m³ (untreated wood) to 1045 kg/m³. Compressive strength and hardness were significantly elevated with higher content of fatty acids in the wood. Microscopy analysis confirmed the presence of the PCM within the wood cells. The treated wood also exhibited a larger time delay during heating and cooling due to the temperature shift in the phase transition. Depending on the concentration of the fatty acid in the wood, the latent heat during melting ranged from 50 to 125 J/g in the temperature from about 24°C to 30°C. These results suggest that the use of the capric acid and stearic acid mixture has a great potential to increase the heat-storage capacity of wood and reduce energy consumption for heating and cooling indoor spaces.

As lignin is becoming more and more attractive to industry and the circular economy continues to grow, the utilization of a byproduct that, to date, has been underrated by the wood industry is investigated as an abundantly available source of lignin. Bark from spruce, larch and beech tress is extracted using the organosolv process with and without prior hot water extraction. The influence of the treatment on chemical properties of the lignin was determined by spectrophotometric, chromatographic, and vibrational spectroscopy. It was found that hot water extraction prior to organosolv extraction influences the chemical composition, antioxidative properties and molecular weight distribution of the obtained extracts. While hot water extracts are rich in flavonoids, organosolv fractions can contain high amounts of organic acids depending on whether they are from a hardwood or softwood source. This investigation lays the foundation for further research into the utilization of byproducts to generate high-value resources.

This work explores the elaboration of wood particle‐based composites incorporating bio‐based phase change materials, with epoxidized linseed oil or clay as a binder. Fire performance evaluation of the novel composites includes an assessment to determine the impact of the addition of boric acid as a fire retardant, as well as the incorporation of recycled paper fibres containing boric acid, and the application of trimethoxymethylsilane coating. The study employs thermogravimetric analysis and cone calorimetry under uniform external irradiance, with a T‐history method to analyse thermal behaviour. Results indicated that fire retardants do not compromise the energy functionality of bio‐based phase change material composites, exhibiting a latent heat of approximately 50 J/g. The density ranges from 750 to 875 kg/m³. The use of clay as a binder improves fire performance, leading to a 60% decrease in total heat release and 52% of the composite mass remaining after analysis. Although enhancing fire performance presents challenges, incorporating wood particles in clay demonstrates a promising potential approach for safe use in building applications, contributing to energy efficiency in indoor heating and cooling. The findings contribute valuable insights into these materials for creating safer and more efficient building solutions, particularly in terms of thermal regulation and fire safety.

Wood surface charring is a treatment method commonly employed to enhance weather protection and aesthetic appearance of building exteriors. This study aims to investigate the differences between two wood surface charring processes: the traditional Japanese method known as Yakisugi and an alternative charring technique industrially manufactured with a gas burner. The objective of the study was to assess whether a thicker layer after Yakisugi treatment has any advantages over a thinner layer after the alternative process. Vibrational spectroscopy techniques including UV resonance Raman (UVRR) and Fourier transform infrared (FTIR) spectroscopy, were utilized in conjunction with X-ray-micro-CT analysis. The findings revealed that ATR-FTIR spectroscopy detected the degradation of carbohydrates and changes in lignin within the charred surface, although both processes exhibited similar vibrational contributions. In contrast, UVRR spectroscopy provided insights into the carbonized layers, revealing spectral differences indicating variations in temperature during the charring processes. X-ray micro-CT analysis visually highlighted significant differences in the coal layers, suggesting distinct combustion profiles. Remarkably, the macrostructure of wood treated with Yakisugi remained intact despite a thicker charred layer compared to the alternative charring techniques. However, further investigations are required to assess the weather stability of the alternative charring method for a comprehensive understanding.

This study investigated the impregnation of beech and thermally modified beech (TMB) with a ternary mixture of capric acid, palmitic acid, and stearic acid as a bio‐based phase change material (BPCM). Finite element method (FEM) was used to complement the experimental analysis by providing new insights into computational methods for simulating the behavior of BPCMs in untreated and TMB. The analyzed specimens namely beech and TMB were impregnated with BPCM; the TMB achieved 54% weight percentage gain (WPG) while untreated beech got 37%. Accordingly, a greater increase in the latent heat was obtained for TMB up to 90 J/g, while for untreated beech with BPCM up to 75 J/g. Impregnated specimens absorbed less moisture at relative humidity of air above 50%, likely caused by the high uptake and hydrophobic nature of the BPCM. The study highlights the research gap in performing mathematical simulations on wood samples with BPCM using material thermal properties derived from differential scanning calorimetry or T‐History analysis. It shows that the direct use of these values for simulations leads to unacceptable outputs that result in high errors. The root mean square error for untreated and TMB samples impregnated with BPCM was in the range from 1.06 to 3.1 while that for untreated samples was in the range from 0.57 to 0.87, indicating that the main challenge in simulating and characterizing the samples is due to the interaction of the phase change material with the wood structure.

Furfuryl alcohol (FA) and lactic acid (LA) are two of the most interesting biomolecules, easily obtainable from sugars and hence extremely attractive for green chemistry solutions. These substances undergo homopolymerization and they have been rarely considered for copolymerization. Typically, FA homopolymerizes exothermically in an acid environment producing inhomogeneous porous materials, but recent studies have shown that this reaction can be controlled and therefore we have implemented this process to trigger the copolymerization with LA. The mechanical tests have shown that the blend containing small amount of FA were rigid and the fracture showed patterns more similar to the one of neat polyfurfuryl alcohol (PFA). This LA-rich blend exhibited higher chloroform and water resistances, while thermal analyses (TG and DSC) also indicated a higher furanic character than expected. These observations suggested an intimate interconnection between precursors which was highlighted by the presence of a small band in the ester region of the solid state ¹³C–NMR, even if the FT-IR did not evidence any new signal. These studies show that these bioplastics are basically constituted of PLA and PFA homopolymers with some small portion of covalent bonds between the two moieties.