Application areas of synchrotron radiation tomographic microscopy for wood research

Abstract

Possible applications for synchrotron radiation tomographic microscopy in the field of wood research were tested and evaluated at the TOMCAT beamline (TOmographic Microscopy and Coherent rAdiology experimenTs) at the Swiss Light Source (SLS) at the Paul Scherrer Institute (Villigen, Switzerland). For this study, small cylindrical samples ([ 1 and 3 mm) were examined with different experimental setups resulting in a nominal voxel size of approximately 1.48 9 1.48 9 1.48 and 3.7 9 3.7 9 3.7 lm 3 , respectively. Suitability of the TOMCAT microscope for 3D investigations of wood anatomy was tested on several softwood and hardwood species revealing microscopic features (e.g. tyloses, wall thickenings or pits) down to the nominal pixel size. The results suggest that even features in the sub-voxel range can be made visible. Tomographic microscopy was also tested for wood technological applications, i.e. penetration behaviour of a wood preservative and also of three wood adhesives (poly-urethane resins) with different viscosities. Although the experiments with the preservative yielded no clear results, the method seems suitable for examining the penetration of the different adhesives. The adhesive penetrates the wood mainly by the vessels where it can be easily discerned from the wood structure.

X-ray computed tomography of wood-adhesive bondlines: attenuation and phase-contrast effects

“…To date, the majority of wood XCT studies have used conventional reconstruction methods, such as the filtered backprojection algorithm, and relied on absorption contrast for material identification and differentiation (Hass et al 2010;Mannes et al 2010;Modzel 2009;Modzel et al 2011;Paris et al 2014;Trtik et al 2007). In microscale analyses, absorption contrast is typically adequate for studying anatomical cellular features in solid wood, as only two materials, air and wood cell wall, are present.…”

Combination of neutron imaging (NI) and digital image correlation (DIC) to determine intra-ring moisture variation in Norway spruce

“…For softwoods, several studies identified strong gradients between earlywood (EW) and latewood (LW) with respect to cell geometry, swelling, shrinkage, elastomechanical properties, and density (Harris and Meylan 1965;Fengel and Stoll 1973;Eder et al 2009;Taguchi et al 2011). High-resolution techniques (0.5-1 μm voxel size), such as micro-computer tomography, offer insight in the 3D response toward moisture changes (Trtik et al 2007;Mannes et al 2010;Derome et al 2011) but are restricted to a few cell layers being simultaneously imaged. Derome et al (2011) found pronounced anisotropic swelling and shrinkage for the low-density EW, with lowest strain in the radial direction, whereas the high-density LW showed an almost isotropic behavior.…”

Synchrotron-based tomographic microscopy (SbTM) of wood: development of a testing device and observation of plastic deformation of uniaxially compressed Norway spruce samples

“…The associated data processing allows acquisition of spatial information even of subcellular structures with a resolution of 0.35 μ m Stampanoni et al 2006a,b ) and observations of different anatomical elements. Both methods provided useful data from in situ mechanical experiments with wood (Trtik et al 2007 ;Walther and Thoemen 2009 ;Hass et al 2010 ;Mannes et al 2010 ), either by means of manual or automatic testing devices (Badel et al 2008 ;Forsberg et al 2008 ). Suitable testing devices seem to be a bottleneck in this type of experiments.…”