Magnetic resonance imaging study of water absorption in thermally modified pine wood

Thermal modification is an environmentally friendly process that enhances the lifetime and properties of timber. In this work, the absorption of water in pine wood (Pinus sylvestris) samples, which were modified by the ThermoWood process, was studied by magnetic resonance imaging (MRI) and gravimetric analysis. The modification temperatures were varied between 180 degrees C and 240 degrees. The data shows that the modification at 240 degrees C and at 230 degrees C decreases the water absorption rate significantly and slightly, respectively, while lower temperatures do not have a noticeable effect. MR images reveal that free water absorption in latewood (LW) is faster than in earlywood (EW), but in the saturated sample, the amount of water is greater in EW. Individual resin channels can be resolved in the high-resolution images, especially in LW regions of the modified samples, and their density was estimated to be (2.7 +/- 0.6) mm(-2). The T-2 relaxation time of water is longer in the modified wood than in the reference samples due to the removal of resin and extractives in the course of the modification process.