Dimensionsstabilitet för asp som modifierats med oxiderad glukos

Abstract: Wood modification is an attractive study topic in the wood industry to improve the properties of wood for outdoor structure applications. Development of environmentally friendly and renewable materials to improve dimensional stability of wood is of high interest.
In this project, Fenton´s reagent was used to oxidize glucose and then small cubes of solid aspen wood was impregnated with the aqueous solution using water vacuum followed by drying/curing by heating in oven. A series of experiment was conducted by DOE (design of experiment) for multivariate statistic analysis on the influence of various processing parameters. Curing temperature, impregnate pH and their interaction effects was found to be important in improving dimensional stability of impregnated wood. A second experiment was performed at high curing temperature of 140oC aiming to achieve highest Anti Swelling Efficiency (ASE). This was performed with larger dimensions of solid wood. Water repellent effectiveness (WRE) and ASE results indicated that the dominate mechanism for reducing the swelling property of wood was more like conditions prevailing under thermal modification of wood such as hemicelluloses degradation.
A third series of experiment was performed aiming at reduce thermal degradation reactions and prove the effect of cell wall bulking and cross-linking effect on ASE. The research results showed that under low temperature heating conditions at 103oC and fairly strong acid conditions (pH 2.4), higher ASE of around 45% was achieved by the wood impregnated with oxidized glucose after one day water soaking rather than when impregnated with oxidized sucrose (ASE was around 35%). An even lower ASE of 10% was obtained for wood treated with Fenton’s reagent. The WPG for oxidized sucrose treated sample was twice as high as the sample with oxidized glucose while the cell wall bulking of oxidized sucrose treated sample was lower than oxidized glucose treated sample. Though large amount of impregnate had been leached out, an ASE of 20% for the wood samples which had been impregnated with oxidized glucose was obtained after 7 days water soaking test. It suggested that under our impregnation and curing treatment, there might be small amount of reactive compounds generated from the glucose oxidization that form possible cross-linking with wood components inside cell wall. From scanning electron microscopy (SEM) pictures, it can be seen that the cell wall thickness of all the impregnated samples were smaller than control aspen samples. Furfural can be detected from the first day of soaking in water of the samples impregnated with Fenton Reagent. The degradation of wood cell wall compounds might occur and could influence the dimensional stability of treated wood under the conditions used in this study. WPG played an important role in inhibiting water uptake, oxidized sucrose impregnated wood with higher WPG showed better WRE than oxidized glucose impregnated samples with a lower WPG.