Erik Larnøy

Variation in treatability of Scots pine ( Pinus sylvestris ) by the chemical modification agent furfuryl alcohol dissolved in water

Scots pine (Pinus sylvestris) sapwood was investigated for variation in treatability using the wood modifying agent, furfuryl alcohol (FA) in water. The variation in treatability within trees, between trees and between different stands of Scots pine was studied. Investigated variables that reduced the residual variance significantly were: site location, latitude of site, height of trees, annual ring width, vertical and horizontal position in the tree and method of drying. Linear mixed model statistics were used and tree number was handled as a random variable. The best model reduced the treatability residual variance by 67%. Location was the single factor affecting treatability most. Differences in latitude between locations may be the reason for that. Latitude correlated negatively with the treatability. Within the trees, the treatability of sapwood increased with distance from ground and with distance from heartwood border. A small, but significantly better treatability was found for kiln dried wood (60°C) compared to air dried wood (20°C).

Detection of chlorine-labelled chitosan in Scots pine by energy-dispersive X-ray spectroscopy

The aim of this study was to use energy-dispersive X-ray spectroscopy (EDX) to localize chitosan in the cell wall of chitosan-impregnated Scots pine. It was of interest to investigate the concentration of chitosan in wood to gain further knowledge and understanding of the distribution of chitosan in the wooden matrix. After deacetylation, chitosan was re-acetylated with chloroacetic anhydride to achieve a covalent bonding of chloride to the chitosan polymer. Chloride-labelled chitosan was measured by EDX using a scanning electron microscope and described as chloride intensity. Analysis of free chloride anions was performed by dialysis and inductively coupled plasma atomic emission spectroscopy. There was a significant correlation between the molecular weight of chitosan and the intensity of covalent-bonded chloride to the chitosan polymer. High molecular weight chitosan showed a better interaction with the cell wall structure than low molecular chitosan.

TREATMENT OF WATERLOGGED ARCHAEOLOGICAL WOOD USING CHITOSAN- AND MODIFIED CHITOSAN SOLUTIONS. PART 1: CHEMICAL COMPATIBILITY AND MICROSTRUCTURE

Abstract Due to problems with most of the existing conservation treatments, new materials for the stabilization of waterlogged archaeological wood are highly desirable. The ideal consolidant should be environmentally friendly and safe to work with for conservators, while strengthening the objects without ruining the visual impression of the wood or filling it in ways that prevent re-treatment in the future. This paper tests chitosan since it is a multifunctional material that not only offers support but also hinders catalytic activity by potentially chelating reactive metal ions. Three solutions of 2% chitosan in 0.1 M acetic acid were chosen as a consolidant for samples from a 1150-year-old piece of waterlogged Viking Age wood from Slagen prestegård. The penetration of chitosan was determined by freeze-drying the samples and analyzing them using high-performance liquid chromatography (HPLC). It was found that chitosan solution penetrated at least 1 cm into the wood along the grain over the span of 2 weeks. Depolymerizing the chitosan only improved uptake slightly. The chitosan left an open structure in the waterlogged archaeological wood. It offered some strength to severely degraded waterlogged wood, but further tests are needed to evaluate stability, shrinkage, and fixation.

Accessibility of hydroxyl groups in anhydride modified wood as measured by deuterium exchange and saponification

Abstract Acetylated wood (WAc) shows improved properties largely due to the reduced amount of water in its cell wall, but the exact mechanism of water reduction remains unclear. Acetylation reduces hydroxyl (OH) content by acetyl (Ac) substitution but may also limit water access to unmodified OH groups by steric hindrance. In the present work, the accessibility of OH groups in acetylated or propionylated Radiata pine (Pinus radiata D. Don) wood (WAc and WPr) was investigated by deuterium exchange, saponification in sodium hydroxide followed by high-performance liquid chromatography (HPLC) analysis and weight percentage gain determination of the modified samples. Acetylation reduced OH accessibility (OHA) to a greater extent than would be predicted, if OH substitution were the only responsible mechanism for accessibility reduction. The combination of deuterium exchange and saponification results provides strong evidence that steric hindrance plays a key role in reduction of water accessibility to unmodified OH groups in WAc. The supramolecular architecture of WPr samples seems to be modified by the propionylation reaction, which leads to increased OHA at low levels of substitution. This suggests that molecular restructuring within the cell wall exposes new OH groups after propionylation. At higher levels of substitution, however, the WPr exhibited less OHA than expected indicating steric hindrance from the propionyl groups.

Variation in treatability of Scots pine sapwood: a survey of 25 different northern European locations

The treatability of Scots pine sapwood sampled from 25 locations in northern Europe, which was impregnated with an experimental furfuryl alcohol mix, was studied. A large variation in treatability was found between stands. The treatability was affected by anatomical properties of the trees and therefore also by the immediate climate, the sociological position of the tree in the stand, growth increments and on-stand competition. With the models applied, most parts of the differences in treatability between stands could be explained, while the treatability variation between trees within a stand remained mostly unexplained. Wider annual rings and higher latewood contents were found to increase the treatability. Models that included data on growth conditions and climate explain more of the variation in treatability, indicating that also other anatomical properties are influencing the treatability. Tree attributes and growth conditions that reduce annual ring width and latewood content decreased the treatability. Trees growing under warmer conditions and developing larger growth increments were easier to impregnate. Wood from trees growing near the timberline and under environmental conditions impairing wood growth was more difficult to treat.