Introduction
Materials and methods
Organo-silicon compounds
Wood samples
Acetylation of wood with ethyltriacetoxysilane
Preparation of an acetoxy-functional polydimethylsiloxane
Acetylation of wood in the presence of organo-silicon compounds
Infrared spectroscopy
Water uptake test
Determination of the acetyl content
Fungal decay test
Bending and impact bending test
Results and discussion
Acetylation with ethyltriacetoxysilane (TAS)
Bulking, WPG and water uptake after modification with various combinations of polysiloxane and acetic anhydride
WPG, bulking and acetyl content after modification with combinations of acetoxy-functional siloxane and acetic anhydride
Water uptake
Fungal decay
Pine sapwood | Beech wood | |||
---|---|---|---|---|
WPG (%) | Mass loss (%) | WPG (%) | Mass loss (%) | |
Control | – | 28.0 (9.8) | – | 25.2 (1.9) |
Acetylation 1 h | 0.5 (0.1) | 33.0 (3.1) | 2.5 (0.4) | 20.1 (1.6) |
Acetylation + siloxane 1 h | 8.6 (0.8) | 35.5 (4.1) | 5.5 (1.2) | 21.5 (2.0) |
Acetylation 2 h | 4.5 (0.3) | 26.0 (4.9) | 10.2 (0.2) |
11.5 (0.9)
|
Acetylation + siloxane 2 h | 12.5 (0.4) | 29.7 (10.4) | 15.6 (0.9) |
14.2 (1.5)
|
Mechanical properties
Bending strength (N mm−2) | Modulus of elasticity (N mm−2) | Impact bending strength (kJ m−2) | WPG (%) | Equilibrium moisture content at 20 °C/65 % RH (%) | |
---|---|---|---|---|---|
Control | 119 (11) | 13,200 (1,276) | 30,285 (7,855) | – | 10.6 (0.1) |
Acetylation | 138 (22) | 13,183 (1,510) | 43,513 (9,992) | 21.0 (0.3) | 5.2 (0.1) |
+1 % Siloxane | 138 (25) | 13,000 (1,669) | 36,310 (9,733) | 21.6 (0.3) | 5.2 (0.1) |
+5 % Siloxane | 122 (26) | 12,256 (1,516) | 40,047 (7,381) | 24.1 (0.2) | 5.2 (0.1) |
+10 % Siloxane | 141 (17) | 13,583 (1,164) | 34,758 (11,945) | 28.7 (0.4) | 5.2 (0.0) |