Masanori Kishino, Takato Nakano
Artificial weathering of tropical woods. Part 2: Color change
This paper describes the change in diffuse reflectance Fourier transform infrared (DRIFT) and ultraviolet-visible (UV-Vis) diffuse reflectance spectra of the following eight tropical woods during artificial weathering up to 600 h in relation to their color changes, especially to yellowing: Amnurana acreana, Acacia auriculiformis, Dipterocarpus spp., Eucalyptus marginata, Eucalyptus robusta, Shorea spp. and Tabebuia spp. with relatively high and low specific gravity. For A. acreana, A. auriculiformis, Dipterocarpus spp. and both Tabebuia spp., ?b* (yellowing) increased with exposure up to 50 h, and decreased above 50 h. For E. marginata, E. robusta and Shorea spp., on the other hand, both ?a* (shift to red) and ?b* decreased with increased exposure time. For woods in which ?b* increased, the ?b* showed a positive dependence on the difference in relative intensity ratio of a band at 1740 cm–1 to that at 2900 cm–1 (?D1740/D2900) in DRIFT spectra of specimens before and after exposure. This result indicated that the increased band at 1740 cm–1 played a significant role in the increased ?b*. Then again, also for woods in which ?b* decreased, the ?D1740/D2900 increased, but was not related to the Db*. The ?D1740/D2900 for woods in which ?b* decreased had a positive relationship to the difference in remission function at 410 nm (?F(R?)410) in UV-Vis diffuse reflectance spectra for specimens before and after exposure, while woods in which ?b* increased were independent of the ?F(R?)410. Therefore, it is suggested that woods in which ?b* increased and decreased differ from one another in the contribution to the increase in the band at 1740 cm–1, resulting in either an increase or decrease of ?b*.
Holzforschung, Walter de Gruyter
Print ISSN: 0018-3830
Volume: 58, 08/2004
Pages: 558 - 565
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