ZIB

Hits per page

hits 1 - 2 | 2 hits

Sorting

Electronic Resource

Proton magnetic resonance techniques for characterization of water in wood: application to white spruce (1992)

Araujo, C. D. ; MacKay, A. L. ; Hailey, J. R. T. ; [et al.]

Springer

Wood science and technology 26 (1992), S. 101-113

add to mindlist on the mindlist

Details

ISSN: 1432-5225

Source: Springer Online Journal Archives 1860-2000

Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics

Notes: Summary Two new proton magnetic resonance techniques, relaxation spectra and relaxation selective imaging, have been used to investigate the distribution of water in samples of normal white spruce sapwood, heartwood, and juvenile wood as well as two rehydrated heartwood samples containing incipient decay and compression wood respectively. It is demonstrated that the spin-spin (T2) relaxation behavior in wood is best presented as a continuous spectrum of relaxation times. Spectra of T2 for white spruce show separate peaks corresponding to the different water environments. Bound water gives a peak with an T2 time of about 1 ms and lumen water gives a distribution of T2 times in the range of 10 to 100 ms. The lumen water T2 time is a function of the wood cell radius. Consequently, the different cell lumen radii distributions for spruce sapwood, juvenile wood, and compression wood are readily distinguishable by the shape of their T2 spectra. Water environments which are separable on a T2 spectrum may be imaged separately. Imaging has been carried out in one dimension for bound water and lumen water of a spruce sapwood sample at four different moisture contents ranging from 100% to 17%. For the first time, we demonstrate that above the fibre saturation point the moisture density profile of the bound water is largely independent of moisture content. The feasibility and utility of using these techniques for internal scanning of logs and lumber is discussed. These techniques should provide new insights into the wood drying process.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF00194466

Permalink

Library	Location	Call Number	Volume/Issue/Year	Availability

Others were also interested in ...

Paper (German National Licenses)

Fulltext

Electronic Resource

An NMR determination of the physiological water distribution in wood during dryingWork supported by the Canadian Forestry Service and the Natural Sciences and Engineering Research Council of Canada. (1987)

Menon, R. S. ; MaCkay, A. L. ; Hailey, J. R. T. ; [et al.]

New York, NY [u.a.] : Wiley-Blackwell

Journal of Applied Polymer Science 33 (1987), S. 1141-1155

add to mindlist on the mindlist

Details

ISSN: 0021-8995

Keywords: Chemistry ; Polymer and Materials Science

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics

Notes: Proton magnetic resonance has been used to study water in Douglas fir and western red cedar. The free induction decay, when combined with a knowledge of chemical composition of the wood, gives an accurate measure of the absolute moisture content. Spin-lattice relaxation was found to be significantly different for the two species. In sapwood, three distinct spin - spin relaxation times, T2, were measured and assigned, with the help of anatomical data, to water in and on the cell wall, water in the ray and latewood tracheid lumens, and water in the earlywood tracheid lumens. This T2 behavior was explained by a model in which free water in a void exchanges with a small fraction of bound water on the lumen surface. The three T2's were almost independent of moisture content, suggesting physically separate compartments. The behavior of the three water components during drying was studied. The fiber saturation point could be determined from a single T2 measurement on a green sapwood sample. Magnetic resonance imaging of logs was investigated.

Additional Material: 5 Ill.