| Project/Area Number |
17580148
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
林産科学・木質工学
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| Research Institution | Forestry and Forest Products Research Institute |
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Principal Investigator |
KATAOKA Yutaka Forestry and Forest Products Research Institute, Department of Wood Improvement, Team Leader (80353639)
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| Co-Investigator(Kenkyū-buntansha) |
KIGUCHI Makoto Forestry and Forest Products Research Institute, Department of Wood Improvement, Laboratory Head (50353660)
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| Project Period (FY) |
2005 – 2007
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| Project Status |
Completed (Fiscal Year 2007)
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| Budget Amount *help |
¥2,770,000 (Direct Cost: ¥2,500,000、Indirect Cost: ¥270,000)
Fiscal Year 2007: ¥1,170,000 (Direct Cost: ¥900,000、Indirect Cost: ¥270,000)
Fiscal Year 2006: ¥800,000 (Direct Cost: ¥800,000)
Fiscal Year 2005: ¥800,000 (Direct Cost: ¥800,000)
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| Keywords | Wood / Surface Properties / Degradation / Photo-Oxidation |
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| Research Abstract |
Wood exposed to sunlight undergoes color changes and surface weakening due to the photo-oxidation that occurs in wood surface layers. Better understanding of the penetration depth to which such degradation extends into wood is desirable because it would allow the development of more effective photo-protective treatments that target the surface layers of wood most susceptible to photodegradation. In this study, FT-IR microscopic depth profile analysis was used to measure the penetration of photo-induced chemical changes into wood during exposure to artificial sunlight for up to 1500h. IR spectra showed that chemical changes penetrated into earlywood of sapwood of Japanese cedar and Japanese cypress to a depth of up to 700μm and 450μm, respectively. There was a logarithmic increase in the depth of photodegradation as a function of irradiation time. Exponential attenuation of light with wood depth may be responsible for the logarithmic increases in thickness of photodegraded layers. It was also suggested that the 700μm-thick photodegraded layer in Japanese cedar may directly be caused by light that penetrated into cedar wood. Parallel experiments assessed the transmission of UV and visible light through Japanese cedar earlywood. It was shown that the penetration of light into wood was positively correlated to its wavelength. Accordingly, the depth of photodegradation in Japanese cedar also increased with wavelength up to and including the violet region of the visible spectrum, but longer wavelength blue light did not have sufficient energy to degrade wood. Thus, violet light was the component of the visible spectrum that extends photodegradation into wood beyond the zone affected by UV radiation. It was also found that there was an inversely proportional relationship between the depth of photodegradation and wood density. The results obtained here are helpful for the prediction of depth of photodegradation in wood.
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