Thermal softening properties of various wood species within an annual ring

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 & DEG;C were focused to clarify the differences in thermal softening properties within an annual ring. The following results were obtained. The peak of tan & delta; caused by micro-Brownian motion of lignin was observed in both EW and LW all species. For softwoods, the peak temperatures of tan & delta; of EW appeared at higher temperatures than those of LW. For hardwoods, in the other hand, the peak temperatures of tan & delta; 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 tan & delta; 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.

Automated summary

This study conducted dynamic mechanical analysis on water-saturated earlywood and latewood of various wood species to investigate the differences in thermal softening properties. The results showed that there were variations in peak temperature and anisotropy in thermal softening properties among different wood species.