Recent Research within the Northern European Network for Wood Science and Engineering—Updates from WSE2019

Abstract

The contributions included in the current Special Issue fall into three broad subject areas within wood science, namely (1) the service life and durability of wood exposed outdoors, (2) wood modifications aimed at increasing resistance to fungal decomposition, and (3) the use of veneer for composite materials. [9] concerns the machining of wood in a process where the shear-cutting of wood veneers is integrated in an injection molding tool. Maria Fredriksson 1,*, Gry Alfredsen 2 and Lisbeth Garbrecht Thygesen 3 1Department of Building and Environmental Technology, Division of Building Materials, Lund University, P.O. Box 118, SE-221 00 Lund, Sweden 2Division of Forest and Forest Resources, Wood Technology, Norwegian Institute of Bioeconomy Research, P.O. Box 115, NO-1431 Ås, Norway 3Department of Geosciences and Natural Resource Management, University of Copenhagen, Rolighedsvej 23, DK-1958 Frederiksberg C, Denmark *Author to whom correspondence should be addressed.

This Special Issue includes selected contributions from the 15th Annual Meeting of the Northern European Network for Wood Science and Engineering (WSE2019), which was held in Lund, Sweden, 9–10 October 2019. The network had its first annual meeting in 2005, and the purpose of the network is to promote collaboration between Northern European researchers within wood science and engineering. Early stage researchers are especially encouraged to participate in the meetings and present their work. The contributions included in the current Special Issue fall into three broad subject areas within wood science, namely (1) the service life and durability of wood exposed outdoors, (2) wood modifications aimed at increasing resistance to fungal decomposition, and (3) the use of veneer for composite materials.

Within the category on service life and durability of wood exposed outdoors, two were field studies. One of these is a comprehensive experimental study on the weathering of outdoor exposed façade materials, which is reported in the article by Alao et al. [1]. Here, bio-based façade materials were exposed outdoors for two years, during which time color changes and check formation were monitored. Another field study is reported by Hundhausen et al. [2], who investigated the use of iron (II) sulfate treatment on wooden façades as a means of obtaining a more homogeneous and faster greying of the surface than what is typically seen for untreated façades. The greying is believed to be due to the formation of iron (III) within the wooden surface. It was found that the artificial greying depended on exposure to sunlight, suggesting a mechanism involving the photolysis of ether bonds in lignin and the subsequent formation of radicals, which then oxidize iron (II) to iron (III). In addition, the category on service life and durability of wood exposed outdoors also includes a study by Brischke and Selter [3]. This article describes work aimed at predicting the service life of wood based on the exposure at a certain location. It was found that such modelling needs to take local topography into account.

In the category on wood modifications aimed at increasing resistance to fungal decomposition, both the study by Beck [4] and the study by Treu et al. [5] concern the treatment of wood with sorbitol and citric acid (SCA), which is believed to form a polymer within the wood structure. The study by Beck [4] showed that the treatment is efficient against both white-rot and brown-rot fungi, but that prolonged leaching due to hydrolysis of the SCA polymer formed takes place. The study by Treu et al. [5] showed that SCA treatment also seems to protect wood against termites and marine borers. This category also includes a study by Yang et al. [6], which concerns a more well-known modification method, i.e., acetylation of wood. The authors tested the sorption properties of wood for which the content of either lignin or hemicellulose was reduced prior to acetylation. The results showed lower hydroxyl accessibility for these samples than theoretically estimated.

The three studies in the category on veneer are rather diverse. The study by Kallakas et al. [7] successfully explored the use of novel underutilized wood species within plywood, while Moritz et al. [8] (2020) calculated the springback effect on molded laminated stacks of beech wood veneers. The study by Reichel et al. [9] concerns the machining of wood in a process where the shear-cutting of wood veneers is integrated in an injection molding tool. The relationships between wood properties, machine settings and damages were shown.

This Special Issue illustrates the variety within current wood research in northern Europe, but also indicates that better utilization of non-durable and underutilized species is a common denominator, at least for part of the ongoing work. Among the nine contributions in this Special Issue, six were presented by students or early stage researchers.

Acknowledgments

The editors of this Special Issue, with contributions from the 15th Annual Meeting of the Northern European Network for Wood Science and Engineering (WSE2019), are grateful to all authors and reviewers who contributed to the papers in this Special Issue. Additionally, we would like to thank Nordic Forest Research (SNS) for providing funding for the conference.

Conflicts of Interest

The authors declare no conflict of interest.

References

1. Alao, P.; Visnapuu, K.; Kallakas, H.; Poltimäe, T.; Kers, J. Natural Weathering of Bio-Based Façade Materials. Forests 2020, 11, 642.

2. Hundhausen, U.; Mai, C.; Slabohm, M.; Gschweidl, F.; Schwarzenbrunner, R. The Staining Effect of Iron (II) Sulfate on Nine Different Wooden Substrates. Forests 2020, 11, 658.

3. Brischke, C.; Selter, V. Mapping the Decay Hazard of Wooden Structures in Topographically Divergent Regions. Forests 2020, 11, 510.

4. Beck, G. Leachability and Decay Resistance of Wood Polyesterified with Sorbitol and Citric Acid. Forests 2020, 11, 650.

5. Treu, A.; Nunes, L.; Larnøy, E. Macrobiological Degradation of Esterified Wood with Sorbitol and Citric Acid. Forests 2020, 11, 776.

6. Yang, T.; Thybring, E.E.; Fredriksson, M.; Ma, E.; Cao, J.; Digaitis, R.; Thygesen, L.G. Effects of Changes in Biopolymer Composition on Moisture in Acetylated Wood. Forests 2020, 11, 719.

7. Kallakas, H.; Rohumaa, A.; Vahermets, H.; Kers, J. Effect of Different Hardwood Species and Lay-Up Schemes on the Mechanical Properties of Plywood. Forests 2020, 11, 649.

8. Sanne, M.; Ahn-Ercan, G.; Pfriem, A. A Mathematical Solution for Calculating the Springback of Laminated Beech Stacks Molded within the Elastic Range. Forests 2020, 11, 725.

9. Reichel, V.; Berlin, W.; Rothe, F.; Beuscher, J.; Dröder, K. Study of Shear-Cutting Mechanisms on Wood Veneer. Forests 2020, 11, 703.