Thermal modification is one of the most researched fields in wood modification. However, majority of the publication processes occur under atmospheric pressure and there is limited knowledge available about thermal modification under elevated pressure. The drying of the wood material can be avoided by treatment under saturated pressure and therefore the initial moisture content of the material has an increasing impact to the material properties after the modification. In this paper, Scots pine sapwood was thermally modified under saturated pressure using three temperatures, 150°C, 160°C and 170°C. The process temperature, process pressure, mechanical properties and swelling properties of two sample types with different initial moisture contents, oven dry state and water saturated state, were compared. Water saturated samples differed from the properties of the oven dry samples in most of the temperatures. The possibility of the different reactions occurring depending on the amount of water during the modification is considered.
Keywords: saturated pressure, Scots pine, thermal modification
Authors
Uimonen T.
School of Chemical Engineering, Aalto University, Espoo
Altgen M.
Kymäläinen M.
Rautkari L.
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