Vol.:(0123456789) 1 3 European Journal of Wood and Wood Products https://doi.org/10.1007/s00107-020-01503-2 ORIGINAL Resistance against subterranean termite of beech wood impregnated with diferent derivatives of glycerol or polyglycerol and maleic anhydride followed by thermal modifcation: a feld test study Mahdi Mubarok 1,2,3  · Holger Militz 2  · I. Wayan Darmawan 3  · Yusuf Sudo Hadi 3  · Stéphane Dumarçay 1  · Philippe Gérardin 1 Received: 29 July 2019 © Springer-Verlag GmbH Germany, part of Springer Nature 2020 Abstract Termite resistance of European beech (Fagus sylvatica) modifed with a combination of chemical and thermal methods was investigated in feld tests. Modifcation was performed by impregnating diferent aqueous solutions of glycerol maleate or polyglycerol maleate at diferent concentrations (10 or 40%, w/w) into the wood, followed by thermal treatment at diferent temperatures (180, 200, or 220 °C). Field tests were conducted for one-year at Bogor, West Java, Indonesia. All wood samples treated with the combination of chemical and thermal modifcations presented signifcantly higher termite resistance than thermally modifed and untreated wood samples. Curing at 200 or 220 °C resulted in better performance with mass losses due to termite attack of less than 5%. 1 Introduction European beech (Fagus sylvatica) is one of the most impor- tant hardwood species in Europe. It covers about 12 million ha of territory in West and Central Europe (Cap Decision 2010), and is particularly abundant in Central Europe with an area of more than 300,000 km 2 (Leuschner et al. 2006). This species is used for various applications such as furniture, fooring, decorating material, siding, chairs, table, tools, toys or musical instruments. However, its low dimensional stability and poor resistance to fungi and insects limit its applications, particularly for exterior purposes like cladding or decking. Much research has been conducted to improve wood dimensional stability and biological durability, includ- ing thermal and chemical modifcation. These processes are considered as environmentally friendly alternatives to classical treatments based on biocides (Schultz et al. 2008; Gérardin 2016). However, most of the thermal modifcation processes improved only dimensional stability and decay durability, termite durability being achieved only with chemical modifcations involving impregnation of wood with huge amounts of chemicals. Acetylated, furfurylated or DMDHEU (1.3-dimethylol-4.5-dihydroxyethyleneurea) modifed wood has been reported to be resistant to termite attack (Hadi et al. 2005; Militz et al. 2011; Bongers et al. 2015). Improving the durability of heat-treated wood to termites might create new uses for this material, latter one being generally not durable (Mburu et al. 2007, Shi et al., 2007, Surini et al. 2012, Sivrikaya et al. 2015). Impregnation with 10% aqueous polyglycerol maleate initially investigated to fx boron (Salman et al. 2014), followed by heating at 200 or 220 °C improved termite resistance of heat-treated wood (Salman et al. 2017). Further studies made by the same group indicated that utilization of glycerol maleate instead of polyglycerol maleate followed by thermal modifcation improved resistance against the subterranean termite Reticu- litermes flavipes in laboratory tests (Mubarok et al. 2019a, b). The termite resistance efcacy of wood initially impreg- nated with a 10 or 40% glycerol or polyglycerol maleate aqueous solution followed by thermal modifcation at difer- ent temperatures (180, 220 and 220 °C) was evaluated under feld test conditions in a tropical area. * Philippe Gérardin philippe.gerardin@univ-lorraine.fr 1 Faculté des Sciences et Technologies, Université de Lorraine, Inra, EA 4370 USC 1445 LERMAB, BP 70239, 54506 Vandoeuvre-lès-Nancy Cedex, France 2 Wood Biology and Wood Product, Faculty of Forestry, Georg-August-Universität Göttingen, Büsgenweg 4, 37077 Göttingen, Germany 3 Wood Sciences and Technology, Faculty of Forestry, Bogor Agricultural University (IPB), Bogor 16680, Indonesia