Material properties and their interrelation in chemically modified clear wood of Scots pine

The mechanical and physical properties of modified wood were assessed experimentally. Timber studs with a cross-section of 45 mm x 70 mm were modified on a semi-industrial scale by four different methods: 1) acetylation (AC) with acetic anhydride; 2) modification with methylated melannine formaldehyde resin (MMF); 3) heat treatment in vegetable oil (HT); and 4) furfurylation (FA). Sapwood of Scots pine (Pinus sylvestris) with test specimen dimensions of 10 x 10 x 200 mm(3) was investigated. A total of 2449 specimens were included in the study. The following properties and their correlations were studied: density, modulus of elasticity (MOEdyn) measured dynamically, equilibrium moisture content (EMC), and swelling behaviour. The properties were measured at humidity levels of 30%, 65%, and 90% RH, while the temperature was kept constant at 23 degrees C. Significant changes in material properties took place. AC increased the density and reduced MOEdyn, EMC and swelling strain. FA increased the density and the swelling coefficient and reduced EMC and swelling strain. HT reduced the EMC, while MMF modification increased it.