Magnetic resonance imaging study of water absorption in thermally modified pine wood

Javed, Muhammad Asadullah; Kekkonen, Päivi; Ahola, Sakari; Telkki, Ville‐Veikko

doi:10.1515/hf-2014-0183

Cited by 38 publications

(30 citation statements)

References 42 publications

(46 reference statements)

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“…In particular, CPMG is a commonly used sequence for determining T 2 relaxation as it reduces effects of magnet inhomogeneity by multiple refocusing of the spins in the transverse plane. Several studies have employed LFNMR for characterising water in both untreated Araujo et al 1992Araujo et al , 1994Cox et al 2010;Flibotte et al 1990;Fredriksson and Thygesen 2017;Labbé et al 2002Labbé et al , 2006Menon et al 1987;Passarini et al 2015;Telkki et al 2013;Elder 2008, 2009) and modified wood (Elder et al 2006;Hietala et al 2002;Javed et al 2015;Kekkonen et al 2014;Elder 2008, 2009). Based on a deconvolution of the decay curves, signals from water in different compartments within the wood structure have been analysed Araujo et al 1992Araujo et al , 1993Fredriksson and Thygesen 2017;Passarini et al 2015) (see Fig.…”

Section: Spectroscopic Techniquesmentioning

confidence: 99%

Experimental techniques for characterising water in wood covering the range from dry to fully water-saturated

2017

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Water plays a central role in wood research, since it affects all material properties relevant to the performance of wood materials. Therefore, experimental techniques for characterising water within wood are an essential part of nearly all scientific investigations of wood materials. This review focuses on selected experimental techniques that can give deeper insights into various aspects of water in wood in the entire moisture domain from dry to fully water-saturated. These techniques fall into three broad categories: (1) gravimetric techniques that determine how much water is absorbed, (2) fibre saturation techniques that determine the amount of water within cell walls, and (3) spectroscopic techniques that provide insights into chemical wood-water interactions as well as yield information on water distribution in the macro-void wood structure. For all techniques, the general measurement concept is explained, its history in wood science as well as advantages and limitations.

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Section: Spectroscopic Techniquesmentioning

confidence: 99%

Experimental techniques for characterising water in wood covering the range from dry to fully water-saturated

2017

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“…While after 20 days the water signals were still very small in the middle of the 220 • C heat-treated sample. After 60 days of immersion, both the untreated and heat-treated samples were not yet fully saturated, but it was observed in the figures that water absorption in latewood was faster than that in earlywood, whether untreated sample or 220 • C heat-treated sample [31,51]. One possible explanation is that the internal diameter of the cell lumen is larger in earlywood than in latewood, and the smaller radius creates a stronger capillary force, which results in faster water absorption in latewood.…”

Section: Profiles and Nmr Imaging Of Absorption Of Free Watermentioning

confidence: 97%

Effect of Heat Treatment on Water Absorption of Chinese fir Using TD-NMR

Gao

Peng

et al. 2018

Applied Sciences

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Knowledge of the dynamic changes in the water absorption process of heat-treated wood is important for providing a scientific basis for the reasonable application of heat-treated wood, especially for outdoor applications. Nuclear magnetic resonance (NMR) techniques provide detailed information about the moisture components and moisture transport processes in wood, which are not available with other methods. In this work, water absorption of untreated and heat treated Chinese fir (Cunninghamia lanceolata [Lamb.] Hook.) heartwood was investigated using various NMR methods. The heat treatment temperatures were varied between 160 °C and 220 °C. According to the spin-spin relaxation time (T2), there were two components of water in the samples heat-treated at 160 °C and 180 °C as well as the untreated sample, while three components of water were found in the samples heat-treated at 200 °C and 220 °C, and the mass of each component was calculated by the integral peak areas of the T2 curve. The amount of bound water and free water in heat-treated samples were less compared to the untreated ones, and the water absorption decreased correspondingly, due to the increasing heat-treated temperature. The results obtained by one dimensional frequency coding indicated that the heat treatment made wood difficult to be accessed by moisture. Besides, NMR images revealed that the free water absorption in latewood was faster than in earlywood, but earlywood could absorb more water than latewood.

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“…heartwood, but the extent of the decrease was different at different moisture levels. Javed et al [77] found that heat treatment at 230 and 240 • C gave higher maximum moisture contents based on dry mass than for untreated references, but the absolute amount of water was always lower in the heat-treated samples. This may be a consequence of the mass loss occurring during thermal treatment; the moisture content can, thus, increase because of the lower dry mass, but without the actual amount of water being higher.…”

Section: Thermal Modificationmentioning

confidence: 98%

“…Imaging techniques can be used to visualize water distributions within the wood structure, including magnetic resonance imaging (MRI) [29,[77][78][79], neutron imaging [80][81][82], and X-ray imaging [83,84]. Of these three, only MRI was used to study location of water at the cell level.…”

Section: Location and State Of Watermentioning

confidence: 99%

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On Wood–Water Interactions in the Over-Hygroscopic Moisture Range—Mechanisms, Methods, and Influence of Wood Modification

Fredriksson

2019

Forests

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Wood is a hygroscopic material that absorbs and desorbs water to equilibrate to the ambient climate. Within material science, the moisture range from 0 to about 95–98% relative humidity is generally called the hygroscopic moisture range, while the exceeding moisture range is called the over-hygroscopic moisture range. For wood, the dominating mechanisms of moisture sorption are different in these two moisture ranges; in the hygroscopic range, water is primarily bound by hydrogen bonding in cell walls, and, in the over-hygroscopic range, water uptake mainly occurs via capillary condensation outside cell walls in macro voids such as cell lumina and pit chambers. Since large volumes of water can be taken up here, the moisture content in the over-hygroscopic range increases extensively in a very narrow relative humidity range. The over-hygroscopic range is particularly relevant for durability applications since fungal degradation occurs primarily in this moisture range. This review describes the mechanisms behind moisture sorption in the over-hygroscopic moisture range, methods that can be used to study the interactions between wood and water at these high humidity levels, and the current state of knowledge on interactions between modified wood and water. A lack of studies on interactions between modified wood and water in the over-hygroscopic range was identified, and the possibility of combining different methods to acquire information on amount, state, and location of water in modified wood at several well-defined high moisture states was pointed out. Since water potential is an important parameter for fungal growth, such studies could possibly give important clues concerning the mechanisms behind the increased resistance to degradation obtained by wood modification.

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Magnetic resonance imaging study of water absorption in thermally modified pine wood

Cited by 38 publications

References 42 publications

Experimental techniques for characterising water in wood covering the range from dry to fully water-saturated

Experimental techniques for characterising water in wood covering the range from dry to fully water-saturated

Effect of Heat Treatment on Water Absorption of Chinese fir Using TD-NMR

On Wood–Water Interactions in the Over-Hygroscopic Moisture Range—Mechanisms, Methods, and Influence of Wood Modification

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