The effect of aging on the ultrastructure of wood

Borgin, K.; Parameswaran, N.; Líese, W.

doi:10.1007/bf00353388

Cited by 54 publications

(31 citation statements)

References 10 publications

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“…Investigations of the effect of weathering on wood, carried out by different researchers, have dealt with several aspects, e.g. colour change (Fengel and Wegener 1984, Sandermann and Schlumbom 1962, Sell and Leukens 1971, erosion (Arnold et al 1992, Feist and Mraz 1978, Feist and Hon 1984, free radicals (Hon et al 1980;Hon and Feist 1981;Hon and Shiraishi 1991), surface wetting characteristics (Kalnins and Knaebe 1992;Kalnins and Feist 1993), anatomical changes (Miniutti 1967, Borgin 1970, 1971, Borgin et al 1975, Derbyshire and Miller 1981, and strength (Derbyshire et al 1995, Raczkowski 1980. Of the whole electromagnetic spectrum, it is only the shortwave and energy-rich region which has a measurable influence on wood and which is thus of technical interest.…”

Section: Introductionmentioning

confidence: 99%

Weathering of Radial and Tangential Wood Surfaces of Pine and Spruce

Sandberg¹

1999

Holzforschung

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SummaryThe development of cracks and changes in appearance have been investigated on radial and tangential surfaces of pine (Pinus silvestris L) and spruce (Picea abies Karst) which have been exposed outdoors for 33 months. The degradation of the surfaces has also been studied at the micro-level. Untreated samples, samples impregnated with a CCA-agent and samples surface treated with linseed oil have been tested. The annual ring orientation is the most important factor for crack development on weathering. The type of wood, impregnation treatment and surface treatment with linseed oil have only a marginal effect on the crack development. No relation has been found between the density of the samples and the crack development. After 33 months of outdoor exposure, tangential surfaces of pine have 13 times more total crack length per unit area than the corresponding radial surfaces. In spruce, the total crack length on the tangential surfaces is 6 times greater than on the radial surfaces. Tangential surfaces of both pine and spruce have a greater number of cracks per unit area and wider cracks than the corresponding radial surfaces. Tangential and radial surfaces show the same colour change in the surface as a result of weathering. On the micro-level, tangential surfaces have more and deeper cracks than radial surfaces. The cracks on the tangential surfaces occur frequently in both earlywood and latewood. On radial surfaces, cracks occur primarily at the annual ring borders, but to a certain extent also in the earlywood. The radial cell wall of the earlywood has a large number of pits which are degraded at an early stage. Decomposition of the cell wall takes place on both radial and tangential surfaces. Cracks arise which follow the S2 fibril orientation in the cell-wall. Delamination in the middle lamella is especially noticeable in the latewood on tangential surfaces. No differences have been observed regarding linseed oil treatment, impregnation or type of wood.

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Section: Introductionmentioning

confidence: 99%

Weathering of Radial and Tangential Wood Surfaces of Pine and Spruce

Sandberg¹

1999

Holzforschung

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“…These studies generally have been made on untreated wood and often with Radiata pine or southern yellow pine. A number of researchers have examined the effect of weathering on the physical structure of wood [8,74,[79][80][81][82][83][84]. Microscopic studies showed characteristic ridges on the S3 wall layer, wall checking, ray and pit degradation, and middle lamella breakdown.…”

Section: Micro-structural Changes Of Untreated Wood During Weatheringmentioning

confidence: 99%

“…Borgin and his co-workers [84] investigated wood samples varying in age from 900 to 4400 years with SEM and found the weakest parts of the structure, and therefore the most susceptible to failure, are the middle lamella SI region and the interfibrillar matrix.…”

Section: Micro-structural Changes Of Untreated Wood During Weatheringmentioning

confidence: 99%

Study on the degradation mechanism of heat-treated wood by UV light /

Huang

2012

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Heat-treated wood is a wood product thermally treated at high temperatures in the range of 180°C and 240°C for its preservation without using any additional chemicals. Heat treatment modifies wood both chemically and physically. Amorphous polysaccharide content (hemicelluloses) decreases, condensation and demethoxylation of lignin take place, and certain extractives are removed. Consequently, heat-treated wood possesses new physical properties such as reduced hygroscopy, improved dimensional stability, better resistance to degradation by insects and micro-organisms, and attractive darker color. These new beneficial and attractive properties make heat-treated wood popular for indoor as well as outdoor applications.However, similar to untreated wood, heat-treated wood is also susceptible to degradation due to environmental conditions. Weathering results in poor aesthetics for heat-treated wood because of the discoloration and surface checking when exposed to UV radiation. However, investigations on the wettability changes, chemical changes, and microscopic changes of heat-treated wood after exposure to artificial weathering are very limited; and there is no publication available in the literature on the degradation taking place due to the weathering of heat-treated North American jack pine, aspen, and birch used in this study.This work was undertaken to study the weathering degradation mechanisms of the three North American regional species (jack pine (Pinus banksiana), aspen (Populus tremuloides\ and birch (Betula papyrifera)) heat-treated under different conditions to understand the chemical and physical changes taking place and to compare these changes with those of untreated controlled samples when they are exposed to artificial weathering with and without water spray for various periods. Several techniques and tools were used such as color measurement, contact angle test for wettability analysis, Fourier transforms infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) for chemical analysis, florescence microscopy (FM), and scanning electron spectroscopy (SEM) for microscopic structural analysis. These provide a great deal of insight into the degradation process.The results show that color changes occurring during weathering of heat-treated woods are due to the increasing lignin condensation and decreasing extractives content on wood surfaces caused by heat treatment. Changes in wettability during weathering of heattreated wood are induced by the combination of surface structural and chemical modifications. Lignin in heat-treated woods is more sensitive to weathering than other components. It is proposed that the weathering mechanism of heat-treated woods consists of the degradation of lignin matrix and extractives, which lightens the wood color. As a result, the color difference between the color of heat-treated wood before weathering and the color of the same wood during weathering increases with exposure time. Then, the leaching of other polymers present on wood surface takes place...

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“…Wood fragments from various objects have been used in past research to identify wood species and to detect changes that may have occurred in the wood. In these studies, the macroscopic structure of the wood samples selected for study was sound and appeared intact (Borgin et al 1975;Nilsson and Daniel 1990). No microbial degradation was found by Borgin et al (1975), but mechanical damage to the wood cell walls was evident.…”

Section: Introductionmentioning

confidence: 97%

“…In these studies, the macroscopic structure of the wood samples selected for study was sound and appeared intact (Borgin et al 1975;Nilsson and Daniel 1990). No microbial degradation was found by Borgin et al (1975), but mechanical damage to the wood cell walls was evident. Separations within the secondary walls and fractures in middle lamellae were observed.…”

Section: Introductionmentioning

confidence: 97%

Assessment of Deterioration in Archaeological Wood from Ancient Egypt

Blanchette

Haight

Koestler

et al. 1994

Journal of the American Institute for Conservation

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The effect of aging on the ultrastructure of wood

Cited by 54 publications

References 10 publications

Weathering of Radial and Tangential Wood Surfaces of Pine and Spruce

Weathering of Radial and Tangential Wood Surfaces of Pine and Spruce

Study on the degradation mechanism of heat-treated wood by UV light /

Assessment of Deterioration in Archaeological Wood from Ancient Egypt

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