The effect of UV-visible light irradiation on the changes in color and chemical composition of the surfaces of Abies alba L. (fir, a softwood), non-modified and chemically modified, was studied. Chemical modification of the wood was performed by reaction with succinic anhydride in xylene at different concentration values. The wood samples were irradiated in air using a rotative device equipped with a middle pressure mercury lamp. Analysis of the color changes in wood surfaces during photo-degradation was carried out by measuring CIELAB parameters. Fourier transform infrared spectroscopy was used to study chemical changes caused by light irradiation. Irradiation modified physical and chemical characteristics of wood surfaces and resulted in rapid color changes, degradation of lignin and increased content of chromophoric groups on the wood surfaces. Color changes (DeltaE(ab)) correlate well with degradation of lignin.
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