ONLINE ISSN 2069-7430 ISSN-L 1841-4737 PRO LIGNO Vol. 11 N° 4 2015 www.proligno.ro pp. 324-329 324 SELECTED PHYSICAL AND MECHANICAL PROPERTIES OF VISCOELASTIC THERMAL COMPRESSED WOOD FROM FAST GROWING POPLAR Stanislav HORNÍČEK Mendel University in Brno, Faculty of Forestry and Wood Technology, Department of Wood Science Zemědělská 1, Brno, Czech Republic; E-mail: stanislav.hornicek@mendelu.cz Peter RADEMACHER Mendel University in Brno, Faculty of Forestry and Wood Technology, Department of Wood Science Zemědělská 1, Brno, Czech Republic Radim ROUSEK Mendel University in Brno, Faculty of Forestry and Wood Technology, Department of Wood Science Zemědělská 1, Brno, Czech Republic Andreja KUTNAR University of Primorska, Andrej Marušič Institute, Muzejskitrg 2, SI-6000 Koper, Slovenia; University of Primorska, Faculty of Mathematics, Natural Sciences and Information Technology Glagoljaška 8, 6000-Koper, Slovenia; E-mail: Andreja.Kutnar@upr.si Frederick A. KAMKE Oregon State University, Department of Wood Science and Engineering 119 Richardson Hall, Corvallis, OR, USA; E-mail: Fred.Kamke@oregonstate.edu Abstract Densification techniques, combined with other treatment processes, helping additionally to improve wood properties, play an important role in wood modification. An innovative example of this combination with other techniques is the viscoelastic thermal compression (VTC) process. In this study, material of poplar wood from fast growing short rotation plantation (SRP), modified by VTC process, was used for investigation and results were compared with non-modified native wood of plantation grown poplar. Selected physical and mechanical properties, i.e., density, equilibrium moisture content (EMC), and modulus of elasticity (MOE) were investigated. The material, used for this investigation, was obtained from plantation grown poplar clone Max-4 (Populus nigra x Populus maximowiczii) from the Czech Republic. Results show that compression and heat treatment of the viscoelastic thermal compression process lead to significant changes in physical and mechanical properties of the treated material. The density of material depends on the degree of densification and has a crucial effect on properties. The goal of this study was to examine the improvement of properties of SRP poplar clone after applying the VTC densification process. Property improvement of plantation grown poplar wood has a huge potential for future use of this low-cost and fast-growing material, which would save high value materials for special uses. Key words: modification of properties; fast growing poplar; viscoelastic thermal compression. INTRODUCTION Densification of wood has been known for several decades; the first patent appeared at the beginning of the 20 th century (Kollmann et al. 1975). Nowadays, it is combined with other treatment processes to improve additional wood properties. An innovative example of this combination is the viscoelastic thermal compression (VTC) process, which is a type of thermal-hydro-mechanical treatment. In this study, material of poplar wood from fast growing short rotation plantation (SRP), modified by the VTC process, was used for investigation. Results were compared with non-modified native wood of plantation grown poplar. Selected physical and mechanical properties, i.e., density, equilibrium moisture content (EMC), swelling / shrinkage and modulus of elasticity (MOE) were investigated.