Analysis of microfibril angle of wood fibers using laser microscope polarimetry

Palviainen, Jari; Silvennoinen, Raimo; Rouvinen, Juha

doi:10.1117/1.1630057

Cited by 5 publications

(7 citation statements)

References 13 publications

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“…Measurement techniques for MFA are of two types, either measurement of individual tracheids or fibres using microscopy, or measurement of bulk wood samples using X-ray diffraction or near infrared (NIR) spectroscopy. Microscopy-based techniques are divided into those that rely on the optical properties of crystalline cellulose, employing variations on polarised light techniques (Preston 1934;Manwiller 1966;Page 1969;El-Hosseiny & Page 1973;Leney 1981;Donaldson 1991;Verbelen & Stickens 1995;Batchelor et al 1997;Ye & Sundström 1997;Jang 1998;Palviainen et al 2004;Ye 2006a, b), and those that directly or indirectly visualise the orientation of the microfibrils themselves. Such methods include iodine precipitation (Bailey & Vestal 1937;Senft & Bendtsen 1985) and other biological, chemical or physical treatments (Huang 1995;Anagnost et al 2000), confocal reflectance microscopy (Donaldson & Frankland 2004), fluorescence microscopy (Marts 1955), micro-Raman spectroscopy (Pleasants et al 1998), scanning electron microscopy (SEM) (Meylan & Butterfield 1978;Abe et al 1991), and transmission electron microscopy (TEM) (Wardrop & Preston 1947;Hodge & Wardrop 1950;Wardrop 1954Wardrop , 1957Frei et al 1957;Harada 1965a, b;Preston 1965;Dunning 1968;Reis & Vian 2004;Donaldson & Xu 2005).…”

Section: Measurement Methodsmentioning

confidence: 99%

Microfibril Angle: Measurement, Variation and Relationships – A Review

Donaldson¹

2008

IAWA J

290

222

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Microfibril angle (MFA) is perhaps the easiest ultrastructural variable to measure for wood cell walls, and certainly the only such variable that has been measured on a large scale. Because cellulose is crystalline, the MFA of the S2 layer can be measured by X-ray diffraction. Automated X-ray scanning devices such as SilviScan have produced large datasets for a range of timber species using increment core samples. In conifers, microfibril angles are large in the juvenile wood and small in the mature wood. MFA is larger at the base of the tree for a given ring number from the pith, and decreases with height, increasing slightly at the top tree. In hardwoods, similar patterns occur, but with much less variation and much smaller microfibril angles in juvenile wood. MFA has significant heritability, but is also influenced by environmental factors as shown by its increased values in compression wood, decreased values in tension wood and, often, increased values following nutrient or water supplementation. Adjacent individual tracheids can show moderate differences in MFA that may be related to tracheid length, but not to lumen diameter or cell wall thickness. While there has been strong interest in the MFA of the S2 layer, which dominates the axial stiffness properties of tracheids and fibres, there has been little attention given to the microfibril angles of S1 and S3 layers, which may influence collapse resistance and other lateral properties. Such investigations have been limited by the much greater difficulty of measuring angles for these wall layers. MFA, in combination with basic density, shows a strong relationship to longitudinal modulus of elasticity, and to longitudinal shrinkage, which are the main reasons for interest in this cell wall property in conifers. In hardwoods, MFA is of more interest in relation to growth stress and shrinkage behaviour.

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Section: Measurement Methodsmentioning

confidence: 99%

Microfibril Angle: Measurement, Variation and Relationships – A Review

Donaldson¹

2008

IAWA J

290

222

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“…The lengths of the tracheid are 2-4 mm. Early and late wood also differ in density and colour [1,2,15].…”

Section: Propagation Of Light In Woodmentioning

confidence: 99%

“…However, light propagation and scattering in wood have been studied. The spectral reflectance and transmittance of dried wood sample of Scots pine were studied by Palviainen [15]. Also light scattering phenomenon on wood surface was experimentally verified by three-dimensional optical grain direction measurement and anisotropy analysis of wood with a diffractive optical element (DOE) was introduced in [15].…”

Section: Propagation Of Light In Woodmentioning

confidence: 99%

Laser transillumination imaging for determining wood defects and grain angle

Nieminen¹,

Heikkinen²,

Räty³

2013

Meas. Sci. Technol.

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Wood defects and grain angle correlate strongly with timber strength and grading. In this study a laser transillumination imaging method was developed to determine wood defects and grain angle. The method uses a near infrared laser light source which illuminates a wood sample with a round beam and the image generated by the light transmitted through the sample is captured for further analysis. In basic and flawless wood, the transmitted light pattern is an ellipse and wood defects and grain angle deviation will change the shape, size and location of the ellipse. The method could be used for determining the strength of wood, grading sawn timber, studying finger and glue joints, estimating moisture and differentiating between heartwood and sapwood.

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“…On the other hand, light microscopy (LM) allows us to investigate relatively large FOV as well as few-decade micron thick sections from three major planes of wood. Light microscopy such as PLM (Leney, 1981;Andersson et al, 2000), DIC microscopy (Anagnost et al, 2002;Peter et al, 2003) and CLSM Palviainen et al, 2004;Sedighi-Gilani et al, 2005) has been used to measure MFA in S2 layer. To obtain appropriate contrast of MF image against background, special sample preparation methods were also applied to the wood fiber specimen prior to image acquisition (Anagnost et al, 2002;Donaldson & Frankland, 2004).…”

Section: Introductionmentioning

confidence: 99%

Investigation of Layered Structure of Fiber Cell Wall in Korean Red Pine by Confocal Reflection Microscopy

Kwon¹

2014

Applied Microscopy

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Layered structures of fiber cell wall of Korean red pine (Pinus densiflora) were investigated by confocal reflection microscopy (CRM). CRM micrographs revealed detailed structures of the fiber cell wall such as S1, S2, and S3 layers as well as transition layers (S12 and S23 layers), which are present between the S1, S2, and S3 layers. Microfibril angle (MFA) measurement was possible for the S2 and S3 layer in the cell wall. The experimental results suggest that CRM is a versatile microscopic method for investigation of layered structures and MFA measurement in individual sub layer of the tracheid cell wall.

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Analysis of microfibril angle of wood fibers using laser microscope polarimetry

Cited by 5 publications

References 13 publications

Microfibril Angle: Measurement, Variation and Relationships – A Review

Microfibril Angle: Measurement, Variation and Relationships – A Review

Laser transillumination imaging for determining wood defects and grain angle

Investigation of Layered Structure of Fiber Cell Wall in Korean Red Pine by Confocal Reflection Microscopy

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