Effect of hemp oil impregnation and thermal modification on European beech wood properties
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ORIGINAL ARTICLE
Effect of hemp oil impregnation and thermal modification on European beech wood properties Jan Baar1 · Martin Brabec1 · Richard Slávik1 · Petr Čermák1 Received: 5 February 2020 / Accepted: 14 October 2020 © Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract Thermal modification of wood is an environment-friendly method, which, among others, enhances wood water related properties, whereas the use of hot oil as a heating medium generally leads to better performance. In this study, European beech wood was hemp oil-impregnated, thermally modified at 200 °C and both ways of treatment were combined. Analysis of the treated wood included the determination of the change in important wood characteristics—colour, hygroscopicity, dimensional stability, bending properties, and decay resistance against white rot. The results indicate that heat treatment combined with oil has influenced the properties of beech wood more than heat treatment itself. In certain cases, the high effectiveness is only relative with regard to mass increase caused by high oil retention.
1 Introduction Wood is a multipurpose natural material with a high economic importance for a number of industrial sectors such as constructions, furniture, packaging, and chemical industry (Rowell 2005). However, its natural biodegradability, dimensional instability and mechanical properties variability are critical for cost-effective performance over the whole service life of wood (Jones and Brischke 2017). The service life of wood is shortened under unfavourable conditions due to fungal activity, moisture-induced dimensional changes and other impacts. To overcome these natural disadvantages of wood and wood-based products, several methods are used. Even though traditional wood protective methods using biocides as chromated copper arsenate (CCA) and creosote are highly effective against biotic and abiotic factors, their usage has become well regulated in EU due to their toxicity resulting in environmental hazards, expensive registration as well as public perception (Ozgenc et al. 2013; Jones and Brischke 2017; Adhikari and Ozarska 2018). Therefore, new and recently invented modification techniques to enhance the material properties are being continuously developed and commercialized (Hill 2006; Sandberg et al. 2017). * Jan Baar [email protected] 1
Department of Wood Science and Technology, Faculty of Forestry and Wood Technology, Mendel University in Brno, Zemědělská 3, 613 00 Brno, Czech Republic
Thermal modification of wood has been recognized as an environmentally friendly and most commercially successful method to enhance its material properties (Hill 2011; Sandberg et al. 2017). Thermal modification carried out at a relatively high temperature (160–250 °C) in different environments (inert atmosphere) results in the degradation of some of the cell wall components (Navi and Sandberg 2012; Šušteršic et al. 2010). The degradation starts by deacetylation, and the release of acetic acid acts as a depolymerization catalys
