Combined analysis of microstructures within an annual ring of Douglas fir (Pseudotsuga menziesii) by dynamic mechanical analysis and small angle X-ray scattering

Dynamic mechanical analysis (DMA) and small angle X-ray scattering (SAXS) measurements of water-saturated wood of Douglas fir (Pseudotsuga menziesii) in the temperature range of 0 ℃ to 100 ℃ were focused to clarify microstructural changes within an annual ring. The following results were obtained. Thermal softening behavior caused by micro-Brownian motion of lignin was observed in both earlywood and latewood. The peaks of tanδ were found at around 95 ℃ for earlywood and at around 90 ℃ for latewood. These results suggested that the structures of lignin in the cell wall were different between earlywood and latewood. SAXS measurements of water-saturated earlywood and latewood in water were performed with precise temperature control. The scattering intensity increased with increasing temperature, indicating that the density of the matrix was reduced at higher temperature. One-dimensional SAXS intensity at the equator, which approximately represents cellulose microfibrils arrangement in the matrix, was intensively analyzed using the WoodSAS model. The result of this model fitting showed that the cellulose microfibril diameter of latewood was higher than that of earlywood. In addition, the value of interfibrillar distance decreased monotonically in the earlywood, while it decreased rapidly in the latewood from 60 ℃ to 90 ℃. The changes in the cellulose microfibril (CMF) diameter and the interfibrillar distance with increasing temperature between earlywood and latewood by SAXS measurement were different. The differences in CMF diameter and inter-fibril distance between earlywood and latewood measured by SAXS also support the hypothesis that lignin structure differs between earlywood and latewood based on the results of DMA measurements

On the Enumeration of Chequered Tilings in Polygons

The Tokyo 2020 Olympic and Paralympic games emblems, called ``harmonized chequered emblems,'' are designed with three kinds of rectangles. We enumerate all such tilings in a dodecagon with a hole

Transition in viscoelastic properties within successive annual rings of radiata pine (Pinus radiata)

Abstract Dynamic mechanical analysis (DMA) measurements of water-saturated radiata pine wood in the temperature range from 0 ℃ to 100 ℃ were focused to clarify the transition in viscoelastic properties within successive annual rings. Four radially consecutive specimens were taken per annual ring and DMA measurements in the tangential direction were performed using these specimens. The following results were obtained. The peak of tanδ caused by micro-Brownian motion of lignin was observed in all samples. The temperature of peak tanδ tended to decrease from earlywood to latewood within an annual ring. The temperature of peak tanδ increased across annual ring boundary. The same trend was repeated within the next annual ring. It was found that the viscoelastic properties transitioned within successive annual rings

Thermal softening properties of various wood species within an annual ring

Abstract Dynamic mechanical analysis (DMA) measurements of water-saturated earlywood (EW) and latewood (LW) of various wood species in the temperature range from 0 to 100 °C were focused to clarify the differences in thermal softening properties within an annual ring. The following results were obtained. The peak of tanδ caused by micro-Brownian motion of lignin was observed in both EW and LW all species. For softwoods, the peak temperatures of tanδ of EW appeared at higher temperatures than those of LW. For hardwoods, in the other hand, the peak temperatures of tanδ were slightly different between EW and LW in the diffuse-porous wood, whereas the temperatures were almost the same in the ring-porous wood. It was found that the difference in peak temperature of tanδ between EW and LW varied greatly among species. The difference in peak temperature between EW and LW was relatively large for softwoods. In addition, the thermal softening properties both in the radial and tangential directions differed depending on the species, so this suggested that there was anisotropy in the thermal softening properties depending on the species

Proposal for a new method for sustainable and advanced utilization of oil palm trunk waste

Abstract A method to more easily separate vascular bundles and parenchyma was investigated for the purpose of proposing a sustainable and advanced utilization of oil palm trunk (OPT). In addition, particleboard made from vascular bundles was produced as one of the effective ways to utilize the obtained vascular bundles. The following results were obtained. A Zephyr rolling equipment was used for separation, and it was found that the vascular bundles could be easily separated with the veneer in a dry state. SEM observations showed that the vascular bundles could be separated while maintaining the tissue structure. However, some parenchyma remained on the surface of the vascular bundles. The presence of starch was also confirmed within the parenchyma. Particleboard was produced using the separated vascular bundles. The MOR and MOE of the three-layered particleboards with long vascular bundles obtained by Zephyr treatment were about 74.2 MPa and 7.3 GPa, respectively, which are much higher than those of previous wood materials made from OPTs. These results may be the result of extracting the potential of vascular bundles. Graphical Abstrac