A more extensive use of wood can reduce the environmental and climatic impact of the building industry. However, flammability limits the application of wood in multi-story and high rise timber buildings. Struvite mineralization has been shown to be a green solution for fire-resistant timber, but the influence of struvite minerals on the mechanical and gluing properties of wood as well as the combustion behavior have not been studied yet. In this work, we investigate the mechanical properties of mineralized wood by compression, bending, and tension tests as well as the gluing properties by tensile shear tests. Evolved gas analysis using GC/MSD system is applied to determine the thermal decomposition behavior of the mineralized wood, and Double shot analysis reveals volatile components of mineralized wood during the thermal decomposition process. The results show that the struvite mineralization treatment is a bulk modification technique that improves the fire resistance of wood. The mineralization can significantly influence the thermal decomposition behavior of wood, which results in an enhanced char formation. This char layer is a fire barrier that slows down the heat and oxygen penetration. The heat penetration rate of wood panels fabricated with mineralized wood is 0.6 mm/min during the cone calorimeter test, which is half of that of the wood panels fabricated with native wood. Transverse strength and stiffness under compression were improved, whereas mechanical loading in the longitudinal direction revealed similar or slightly decreased strength and stiffness. The mineralization had a minor impact on the gluing properties of solid wood. Wood mineralization by struvite may enable the more extensive use of wood in the construction sector as a substitute to less eco-friendly building materials.
Early industrialization and the development of cheap production processes for paper have led to an exponential accumulation of paper-based documents during the last two centuries. Archives and libraries harbor vast amounts of ancient and modern documents and have to undertake extensive endeavors to protect them from abiotic and biotic deterioration. While services for mechanical preservation such as ex post de-acidification of historic documents are already commercially available, the possibilities for long-term protection of paper-based documents against fungal attack (apart from temperature and humidity control) are very limited. Novel processes for mechanical enhancement of damaged cellulosic documents use Ionic Liquids (IL) as essential process components. With some of these ILs having azole-functionalities similar to well-known fungicides such as Clotrimazole, the possibility of antifungal activities of these ILs was proposed but has not yet been experimentally confirmed. We evaluated the potency of four ILs with potential application in paper restoration for suppression of fungal growth on five relevant paper-infesting molds. The results revealed a general antifungal activity of all ILs, which increased with the size of the non-polar group. Physiological experiments and ultimate elemental analysis allowed to determine the minimal inhibitory concentration of each IL as well as the residual IL concentration in process-treated paper. These results provide valuable guidelines for IL-applications in paper restoration processes with antifungal activity as an added benefit. With azoles remaining in the paper after the process, simultaneous repair and biotic protection in treated documents could be facilitated.
In this study, the interactions between a phenol–formaldehyde resorcinol (PRF) adhesive and water-extractable wood constituents were investigated using combined in-situ FTIR spectroscopy and rheology analysis for a simultaneous examination of the progress of chemical reactions and coherent changes in rheological properties during adhesive curing. Complementary evolved gas analysis and pyrolysis gas chromatography/mass spectroscopy (Py-GC/MS) were performed to detect differences in the final crosslinking and chemical composition of the cured adhesive, respectively. The rheological and chemical analysis results correlated with the tensile shear strength of wood-PRF assemblies. The results showed that adhesive curing was significantly affected by the presence of acidic wood extractives. In particular, the acidic extractives of chestnut wood led to a delay in the resin curing and less final crosslinking of the cured adhesive. This was most likely caused by a reduction in the catalytic effect of the base-catalyzed curing of the adhesive rather than by direct chemical reactions between the extracts and adhesive. These findings can be useful for adapting the resin formulation to the chemistry of acidic wood species.
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