Wood is an inherently hygroscopic material which tends to absorb moisture from its surrounding. Moisture in wood is a determining factor for the quality of wood being employed in construction, since it causes weakening, deformation, rotting, and ultimately leading to failure of the structures resulting in costs to the economy, the environment, and to the safety of residents. Therefore, monitoring moisture in wood during the construction phase and after construction is vital for the future of smart and sustainable buildings. Employing bio-based materials for the construction of electronics is one way to mitigate the environmental impact of such electronics. Herein, a bio-graphene sensor for monitoring the moisture inside and around wooden surfaces is fabricated using laser-induced graphitization of a lignin-based ink precursor. The bio-graphene sensors are used to measure humidity in the range of 10% up to 90% at 25 °C. Using laser induced graphitization, conductor resistivity of 18.6 Ω sq−1 is obtained for spruce wood and 57.1 Ω sq−1 for pine wood. The sensitivity of sensors fabricated on spruce and pine wood is 2.6 and 0.74 MΩ per % RH. Surface morphology and degree of graphitization are investigated using scanning electron microscopy, Raman spectroscopy, and thermogravimetric analysis methods. © 2023 The Authors. 

The present study investigates the ageing performance of a UV protective system for wood, comprising the reactive UV absorber 2-hydroxy-4(2,3-epoxypropoxy)-benzophenone (HEPBP) and epoxy functional vegetable oils (linseed and soybean oil). Scots pine samples of radial or cross-sectional surfaces were treated using a combination of the two components, or using only one of the oils. The treated samples were then aged in a Weather-Ometer for 2 × 60 h and analysed using VPSEM to follow the degradation of the wood substrate in the exact same spot before, during and after ageing. The results of the radial surfaces show slightly less degradation of samples treated with a combination of HEPBP and oil, and for the cross-sectional surfaces an even stronger protective effect is visible. For samples treated with only one of the two oils, no improvement was detectable. The radial surfaces were also analysed using FTIR where the results indicate presence of the protective treatment even after 120 h of exposure. Overall the combined pretreatment of HEPBP and epoxy functional linseed oil was concluded to have a photostabilising effect of the wood substrate.

The present work investigates the photostabilising effect of a pretreatment consisting of 2-hydroxy-4(2,3-epoxypropoxy)-benzophenone (HEPBP) and epoxy functionalized soybean oil (ESBO), reacted on to Scots pine veneers coated with two different acrylic top coats. Two different pretreatment procedures were used, varying in reaction time and temperature. Results from FTIR and SEC analysis indicate that a large amount of reactant was present on the veneers after treatment with either of the two reaction procedures. Furthermore, coating of the pretreated surfaces was possible and the pretreatment does not seem to affect the adhesion between the coating and the wood substrate. Both accelerated ageing and natural exposure was used to study the resistance to photodegradation, and the results were analysed using colour measurements, FTIR and SEM. These analyses all show that 1400 h of accelerated ageing degrades neither the wood nor the coating to any larger extent. However, after 4000 h of UV exposure some signs of degradation are visible but to a lesser extent for pretreated samples. For the samples exposed to natural weathering during 14 months the performance was good in terms of photostabilisation, however all samples suffer from mould to different extents. Pretreated samples show smaller and more evenly distributed areas of mould compared to the references, which show slightly more mould. The combined coating/pretreatment system is thus assumed to have an effect in terms of photostabilization of the coated wood.

This study investigates the photostabilizing effect of the reactive UV-absorber 2-hydroxy-4(2,3-epoxypropoxy)-benzophenone (HEPBP) when used as a primer for wood. The present work further includes a study on the effect of HEPBP used in combination with an epoxy functionalized vegetable oil as a primer system. The study is based on reactions performed on pine veneers using 3-pentanone as a solvent and 4-(dimethylamino)pyridine (DMAP) as a catalyst, varying the reaction time and temperature. Results from FTIR and SEC measurements indicate that a desired reaction between HEPBP and wood does occur and that there are synergetic effects when HEPBP and oil are combined. Color measurements also indicate that the use of HEPBP and epoxidized soybean oil as pretreatment for wood results in a lower color change after 400 h of artificial weathering. We conclude that using HEPBP in combination with epoxy functionalized soybean oil does improve photostability of wood exposed to artificial weathering.

Lignin is a natural polymer and one of the most abundant materials on earth. Despite this fact, lignin is often viewed as a by-product in chemical pulp processing and the use of lignin as a sustainable material is low. However, research and public awareness of sustainability have opened up new possibilities for using lignin as a material. In this study, Kraft softwood lignin was reacted with acetic and propionic anhydride to synthesize esterified lignin. Reactions were performed at 80 °C. The product was analyzed using IR, DSC and processability parameters, such as melt viscosity. The product was then blended with LDPE and extruded into composite films. The films were analyzed using FTIR and TGA, and the mechanical properties were determined by tensile tests. Preliminary results are positive and further studies are planned to confirm the results and establish the range of properties attainable.