Abstract
The microstructural changes in a selection of softwoods and hardwoods resulting from thermo-hydro treatment (THT) at 160°C were examined by means of a state-of-the-art micro X-ray computed tomography. A dedicated X-ray scanning and volumetric processing protocol was developed. All reconstructed volumes had an approximate voxel pitch between 0.8 and 1.2 μm3. The microstructures of the same needle-shaped specimens before and after THT were visualized, and the individual parameters (maximum opening and lumen volume) for various cell types were quantified and compared. The highest values of substance volume were recorded for the ash sapwood (81%) and spruce specimens (72%). After THT, a significant correlation was found between the mass loss determined by gravimetry and the X-ray volume loss. The largest change occurred in the lumen volume of several tissue components, such as libriform fibers, tracheids, and ray parenchyma. The average aspen fiber volume reduction after THT was 31%, a value 2.6 times higher than the volume reduction of the average vessels. The porosity of ash sapwood increased from 41 to 56%, whereas the porosity of birch decreased from 34 to 29%.
Acknowledgments
The authors express their appreciation to COST Action FP0802, FP0904, and FP1006, specifically to its chairs Professor Karin de Borst, Professor Parviz Navi, and Dr. Stefanie Wieland, for providing financial support for the STSMs. We also thank all members of the Laboratory of Wood Technology (Woodlab) at the Faculty of Bioscience Engineering at Ghent University (UGent) for their help.
References
Baensch, F., Zauner, M., Sanabria, S.J., Sause, M.G.R., Pinzer, B.R., Brunner, A.J., Stampanoni, M., Niemz, P. (2015) Damage evolution in wood: synchrotron radiation micro-computed tomography (SRμCT) as a complementary tool for interpreting acoustic emission (AE) behavior. Holzforschung 69:1015–1025.10.1515/hf-2014-0152Search in Google Scholar
Biziks, V., Andersons, B., Belkova, L., Kapača, E., Militz, H. (2013) Changes in the microstructure of birch wood after hydrothermal treatment. Wood Sci. Technol. 47:717–735.Search in Google Scholar
Boone, M., De Witte, Y., Dierick, M., Van den Bulcke, J., Vlassenbroeck, J., Van Hoorebeke, L. (2009) Practical use of the modified Bronnikov algorithm in micro-CT. Nucl. Instrum. Methods Phys. Res. Sect. B Beam Interact. Mater. Atoms 267:1182–1186.Search in Google Scholar
Boonstra, M.J., Tjeerdsma, B.F. (2006) Chemical analysis of heat-treated softwoods. Holz Roh-Werkst. 64:204–221.10.1007/s00107-005-0078-4Search in Google Scholar
Bourgois, J., Bartholin, M., Guyonnet, R. (1989) Thermal treatment of wood: analysis of obtained product. Wood Sci. Technol. 23:303–310.Search in Google Scholar
Brabant, L., Vlassenbroeck, J., De Witte, Y., Cnudde, V., Boone, M.N., Dewanckele, J., Van Hoorebeke, L. (2011) Three-dimensional analysis of high-resolution X-ray computed tomography data with Morpho+. Microsc. Microanal. 17:252–263.10.1017/S1431927610094389Search in Google Scholar PubMed
Bugani, S., Modugno, F., Łucejko, J.J., Giachi, G., Cagno, S., Cloetens, P., Janssens, K., Morselli, L. (2009) Study on the impregnation of archaeological waterlogged wood with consolidation treatments using synchrotron radiation microtomography. Anal Bioanal. Chem. 395:1977–1985.Search in Google Scholar
De Witte, Y., Boone, M., Vlassenbroeck, J., Dierick, M., Van Hoorebeke, L. (2009) Bronnikov-aided correction for X-ray computed tomography. J. Opt. Soc. Am. A Opt. Image Sci. Vis. 26:890–894.Search in Google Scholar
Dierick, M., Van Loo, D., Masschaele, B., Boone, M., Van Hoorebeke, L. (2010) A LabVIEW® based generic CT scanner control software platform. J. X-ray Sci. Technol. 18:451–461.Search in Google Scholar
Dierick, M., Van Loo, D., Masschaele, B., Van den Bulcke, J., Van Acker, J., Cnudde, V., Van Hoorebeke, L. (2014) Recent scanner developments at UGCT. Nucl. Instrum. Methods Phys. Res. Sect. B Beam Interact. Mater. Atoms 324:35–40.Search in Google Scholar
Dietrichs, H.H., Sinner, H., Puls. J. (1978) Potential of steaming hardwoods and straw for feed and food production. Holzforschung 32:193–199.10.1515/hfsg.1978.32.6.193Search in Google Scholar
Endo, R., Sugiyama, J. (2013) Evaluation of cell wall reinforcement in feather keratin-treated waterlogged wood as imaged by synchrotron X-ray microtomography (μXRT) and TEM. Holzforschung 67:795–803.10.1515/hf-2012-0181Search in Google Scholar
Fengel, D. (1966) On the changes of the wood and its components within the temperature range up to 200°C – part 2. Holz Roh-Werkst. 24:98–109.10.1007/BF02608355Search in Google Scholar
Filló, Z., Peres, T. (1970) Holztechnologie 11:270–273. Cited in Fengel and Wegener (1989).Search in Google Scholar
Goring, D.A.I. (1963) Thermal softening of lignin, hemicellulose and cellulose. Pulp Pap. Canada 517–527.Search in Google Scholar
Grinins, J., Andersons, B., Biziks, V., Andersone, I., Dobele, G. (2013) Analytical pyrolysis as an instrument to study the chemical transformations of hygrothermally modified wood. J. Anal. Appl. Pyrol. 103:36–41.10.1016/j.jaap.2012.10.016Search in Google Scholar
Hass, P., Wittel, F.K., McDonald, S.A., Marone, F., Stampanoni, M., Herrmann, H.J., Niemz, P. (2010) Pore space analysis of beech wood: the vessel network. Holzforschung 64:639–644.10.1515/hf.2010.103Search in Google Scholar
Leppänen, K., Bjurhager, I., Peura, M., Kallonen, A., Suuronen, J.-P., Penttilä, P., Love, J., Fagerstedt, K., Serimaa, R. (2011) X-ray scattering and microtomography study on the structural changes of never-dried silver birch, European aspen and hybrid aspen during drying. Holzforschung 65:865–873.10.1515/HF.2011.108Search in Google Scholar
Oliveira, V., Van den Bulcke, J., Van Acker, J., de Schryver, T., Pereira, H. (2016) Cork structural discontinuities studied with X-ray microtomography. Holzforschung 70:87–94.10.1515/hf-2014-0245Search in Google Scholar
Peng, G., Jiang, Z., Liu, X., Fei, B., Yang, S., Qin, D., Ren, H., Yu, Y., Xie, H. (2013) Detection of complex vascular system in bamboo node by X-ray μCT imaging technique. Holzforschung 68:223–227.10.1515/hf-2013-0080Search in Google Scholar
Scholz, G., Zauer, M., Van den Bulcke, J., Van Loo, D., Pfriem, A., Van Acker, J., Militz, H. (2010) Investigation on wax-impregnated wood. Part 2: study of void spaces filled with air by He pycnometry, Hg intrusion porosimetry, and 3D X-ray imaging. Holzforschung 64:587–593.10.1515/hf.2010.090Search in Google Scholar
Svedström, K., Bjurhager, I., Kallonen, A., Peura, M., Serimaa, R. (2011) Structure of oak wood from the Swedish warship Vasa revealed by X-ray scattering and microtomography. Holzforschung 66:355–363.Search in Google Scholar
Thomasi, C., Manduchi, R. (1998) Bilateral filtering for gray and color images. Proceedings of the 1998 IEEE International Conference on Computer Vision, Bombay, India.Search in Google Scholar
Taylor, A., Plank, B., Standfest, G., Petutschnigg, A. (2013) Beech wood shrinkage observed at the micro-scale by a time series of X-ray computed tomographs (μXCT). Holzforschung 67: 201–205.10.1515/hf-2012-0100Search in Google Scholar
Van den Bulcke, J., Boone, M., Van Acker, J., Stevens, M., Van Hoorebeke, L. (2009) X-ray tomography as a tool for detailed anatomical analysis. Ann. For. Sci. 66:508.Search in Google Scholar
Van den Bulcke, J., Biziks, V., Andersons, B., Mahnert, K.C., Militz, H., Van Loo, D., Dierick, M., Masschaele, B., Boone, M., Brabant, L., De Witte, Y., Vlassenbroeck, J., Van Hoorebeke, L., Van Acker, J. (2013) The potential of X-ray computed tomography for 3D anatomical analysis and microdensitometrical assessment in wood research with focus on wood modification. Int. Wood Prod. J. 4:183–190.10.1179/2042645313Y.0000000046Search in Google Scholar
Vlassenbroeck, J., Dierick, M., Masschaele, B., Cnudde, V., Van Hoorebeke, L., Jacobs, P. (2007) Software tools for quantification of X-ray microtomography at the UGCT. Nucl. Instrum. Methods Phys. Res. A 580:442–445.Search in Google Scholar
Zaman, A., Alén, R., Kotilainen, R. (2000) Heat behaviour of Pinus sylvestris and Betula pendula at 200–230°C. Wood Fiber Sci. 32:138–143.Search in Google Scholar
Zauner, M., Keunecke, D., Mokso, R., Stampanoni, M., Niemz, P. (2012) Synchrotron-based tomographic microscopy (SbTM) of wood: development of a testing device and observation of plastic deformation of uniaxially compressed Norway spruce samples. Holzforschung 66:973–979.10.1515/hf-2011-0192Search in Google Scholar
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