Hysteretic swelling of wood at cellular scale probed by phase-contrast X-ray tomography

A critical discussion of the physics of wood–water interactions

“…On this level, the swelling of latewood in the transverse directions is similar (Murata and Masuda 2006;Derome et al 2011). For earlywood, however, the swelling in the tangential direction is similar to that of latewood, whereas the swelling in the radial direction is significantly lower (Derome et al 2011). This may be caused by rays, which are oriented in the radial direction, restraining swelling of the thin-walled earlywood cells more than swelling of the stiffer, thick-walled latewood cells (Ma and Rudolph 2006;Derome et al 2011).…”

“…For earlywood, however, the swelling in the tangential direction is similar to that of latewood, whereas the swelling in the radial direction is significantly lower (Derome et al 2011). This may be caused by rays, which are oriented in the radial direction, restraining swelling of the thin-walled earlywood cells more than swelling of the stiffer, thick-walled latewood cells (Ma and Rudolph 2006;Derome et al 2011). On the macroscopic scale, swelling in the two transverse directions also differs in that tangential swelling is greater than radial swelling.…”

“…The macroscopic swelling of wood in the tangential direction has been found to be directly proportional to swelling at the cell wall level (Murata and Masuda 2006). On this level, the swelling of latewood in the transverse directions is similar (Murata and Masuda 2006;Derome et al 2011). For earlywood, however, the swelling in the tangential direction is similar to that of latewood, whereas the swelling in the radial direction is significantly lower (Derome et al 2011).…”

“…On the macroscopic scale, swelling in the two transverse directions also differs in that tangential swelling is greater than radial swelling. Swelling in the longitudinal direction of softwood is for normal wood significantly lower (Hunt and Shelton 1988;Derome et al 2011) than in transverse directions because the microfibrils are aligned more or less in the longitudinal direction of the wood. In the range 5-20 % moisture content, the relation is linear between swelling of wood and amount of moisture both on macroscale (Stamm 1959;Hartley and Avramidis 1996) and microscale (Ma and Rudolph 2006;Murata and Masuda 2006).…”

Comparison of two single-image phase-retrieval algorithms for in-line x-ray phase-contrast imaging

“…Of these methods, MBA and SPAR are the most widely applicable [25] and are used on a regular basis at the Ghent University Center for Tomography (UGCT) [26] and at other facilities [27,28] for various applications [29,30]. Both methods are implemented in the in-house developed commercially available software package Octopus (inCT, Belgium, [31]).…”