Sodium silicate coated wood
Published: 2010
Publication Name: Proceedings of the International Convention of Society of Wood Science and Technology and United Nations Economic Commission for Europe -- Timber Committee
Publication URL: https://www.swst.org/wp/meetings/AM10/pdfs/WS-59%20Peng%20Yucheng%20Paper.pdf
Abstract:
The objective of this study is to investigate the effect of treatment of wood with inorganic silicon
compounds. Water glass, an alkali silicate has been shown to enhance the physical properties
of wood, such as dimensional stability, hardness, decay resistance, and fire resistance. However,
the high hygroscopicity of water glass also creates some drawbacks: 1) absorption of moisture, 2)
reduction in bending strength due to the drying process, and 3) high chemical leaching when
exposed to water. Using an appropriate drying process for water glass soaked wood showed high
water repellency and high fire resistance. The author derived a drying process to treat sodium
silicate solution impregnated southern pine (Pinus spp.) samples. The effect of cellulose
nanofibrils added in the treating solution was also studied. The mechanical test results for the
treated samples showed that the flexural modulus of rupture (MOR) and modulus of elasticity
(MOE) increased significantly. The effect increased with increasing concentration of sodium
silicate. The highest MOR and MOE of the treated samples were 170.4±12.96 MPa and
18.76±0.93 GPa while the controls were 97.62±8.05 MPa and 10.96±1.15 GPa, increased by 75
% and 71 %, respectively. A study of water vapor uptake indicated that the treatment decreased
the moisture absorption of solid wood. The fracture surfaces of the flexural samples showed the
deposition of silicate in the wood cell lumina. The presence of cellulose nanofibrils in the
sodium silicate solution did not change the properties of the treated wood samples.