Abstract:The common method to impregnate wood with polyethylene glycol (PEG) is to store the samples for several weeks in aqueous PEG-solution, allowing for diffusion of PEG into the wood. As this method is poorly suited for industrial application, an alternative approach based on vacuum-pressure treatment is evaluated in the present study. Using European oak wood and three variants of PEG, including silane-functionalized PEG, impregnation experiments at different PEG concentrations were performed. Significant uptake of PEG resulted in clearly altered wood-water relations and improved dimensional stability of oak wood. These results are discussed in terms of stability in humid and aqueous environments, and in terms of effects of the anatomy of oak wood on differences in dimensional stabilization observed along the radial and tangential anatomical directions, respectively. While both of the PEG variants perform better with an anti-shrinkage efficiency of up to 80%, the PEG-silane variant performs less effectively in this respect; however PEG-silane is clearly predominant in case of water extraction.

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The main purpose of this study was to investigate the hydrophobic effect and chemical changes induced by thermo-treatment and alkyl ketene dimer (AKD) on the surface properties of Alder (Alnus cordata (Loisel) Duby) wood before and after an artificial weathering test. Thermal treatment was conducted at a temperature of 200 °C for 4 h in a thermo-vacuum cylinder. Then, the paper sizing agent, AKD at different concentrations of a solution of 0.1%, 0.5% and 10% was used as a potential hydrophobizing reagent for untreated and thermally treated alder wood surfaces. The contact angle measurement, ATR-FTIR analysis and colour variation were carried out for the samples. The preliminary results revealed that the contact angle values of the wood materials increased with thermal modification. However, the influence of the thermal treatment on hydrophobicity was small when compared to the substantial effect of the AKD application in this respect, and also after the artificial weathering test. The FTIR analysis supported the hypothesis that AKD could make bonds chemically stable even when using a small concentration of AKD. The findings acquired in this work provide important information for future research and the utilization of the AKD on lesser-used wood species.

Purpose Improving technical properties and the durability of wood-based products by modification in various processing technologies is subject to recent research and development activities. This study aimed at integrating environmental considerations during the research and development phase of a novel modification process for a multilayer wood parquet. Due to expected challenges when applying Life Cycle Assessment (LCA) in this phase, the eco-profile of the modified multilayer wood parquet was referred to the original multilayer parquet by estimating payback period and identifying other payback options. Methods An LCA was conducted during the research and development phase of the modification process at laboratory scale and is characterized as ex ante environmental screening of a newly developed technology. The environmental assessment of new products and manufacturing processes during the research and development phase, however, faces multifarious challenges, such as the definition of a functional unit and the service life length. In order to overcome these challenges, the idea was to answer the question under which circumstances the modification process pays back from the perspective of non-renewable energy use and global-warming potential. Aside from investigation of payback period, the feasibility of other payback options was systematically searched. Results and discussion The extra resource input and the resulting increase in environmental burden of the modification of the multilayer parquet can be justified with the extension of service life length by 10 to 20 %, referring to global warming potential and non-renewable energy use, respectively. Other payback options found were adjusting chemical loading during modification, making renovations superfluous, or reducing transport effort. Other than transportation and renovation, which are user-dependent, only the modification lies within the scope of the parquet producer. Conclusions The payback concept is found suitable for comparative estimations on the magnitude of change in environmental performance of product variants during research and development. By investigating on multiple payback options, it was enabled to frame the change in environmental performance, which is essential in order to define the scope of further research and development in a target-oriented way. The possibility of using LCA for an environmental technology valuation at an early stage in product and process development is demonstrated in this study.

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