Multiple swelling of pinewood (Pinus Sylvestris) in binary and ternary mixtures of ethanol, acetone and water

Samples of pinewood (Pinus Sylvestris) were swelled in ternary mixtures of ethanol-acetone-water. The tangential, radial and longitudinal swelling was measured and volumetric swelling of oven-dried samples was determined. Anomalous properties of binary and ternary liquid systems have cardinal influence on swelling of wood. Swelling in solutions was multiplied applying the same samples and a new solution with the same concentrations. Selected specimens were swelled in the same solution repeatedly to perform comparative tests. The values for re-swelling in new solutions were up to two times higher when the same solutions were used. Re-swelling resulted in gradual damping in swelling values. The SEM analysis showed that multiple swelling of wood in water causes decrease in the elasticity of the wood matter. The view of the latewood cells swelled in ethanol and acetone showed the disruption of compound middle lamella (CML). The enlargement of the cell apexes showed deeper impact of the water in ethanol-water mixture. When single swelling of wood in acetone-water mixtures did not reveal any substantial change in the wood structure, multiple swelling caused noticeable swelling of the S3 layer of the cell wall.