Yellowing and IR-changes of spruce wood as result of UV-irradiation

The yellowing and IR-changes of spruce wood as a result of UV-irradiation were studied using two different types of xenon lamps ( λ>300 nm; I o=50 mW cm −2 and λ>280 nm; I o=17.5 mW cm −2). Changes in the IR spectra as well as the yellowing of the irradiated wood surfaces show the influence of...

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Bibliographic Details
Published in:Journal of photochemistry and photobiology. B, Biology Biology, 2003-02, Vol.69 (2), p.97-105
Main Authors: Müller, Uwe, Rätzsch, Manfred, Schwanninger, Manfred, Steiner, Melanie, Zöbl, Harald
Format: Article
Language:English
Subjects:
Color
Dose-Response Relationship, Radiation
FT-IR
Infrared Rays
Irradiation
Lignin
Lignin - analysis
Lignin - chemistry
Lignin - radiation effects
Photodegradation
Photoyellowing
Picea - chemistry
Picea - radiation effects
Plant Stems - chemistry
Plant Stems - radiation effects
Spectroscopy, Fourier Transform Infrared - methods
Ultraviolet Rays
UV-light
Wood
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Summary:The yellowing and IR-changes of spruce wood as a result of UV-irradiation were studied using two different types of xenon lamps ( λ>300 nm; I o=50 mW cm −2 and λ>280 nm; I o=17.5 mW cm −2). Changes in the IR spectra as well as the yellowing of the irradiated wood surfaces show the influence of UV light on the wood modules. The UV-irradiation (72 h; λ>300 nm; I o=50 mW cm −2) decreased the lignin content on the surface by up to 20% of the original values. The colour difference of yellowing (Δ E) exhibited a systematic trend to higher values with increasing irradiation time. Our results show that the photoyellowing (UV–Vis detection) correlates very well with lignin degradation (IR detection). This result is in agreement with the quinone formation as the chromophoric reaction product of lignin decay. The degradation, yellowing, and oxidation kinetics differed only little using different light sources. The absorbed light intensity, which depends on wavelength, the intensity distribution of the light source and the absorption spectrum of lignin, influenced the degradation rate. Under the current experimental conditions, the absorption spectrum of lignin was the most important factor. Therefore, irradiation with λ>280 nm is useful for rapidly monitoring the UV-degradation of wood
ISSN:1011-1344
1873-2682
DOI:10.1016/S1011-1344(02)00412-8