Effects of UV light irradiation on color changes in thermally modified rubber wood based on FTIR

Abstract

To evaluate the effects of chemical changes during thermal modification on the resistance of wood against photodegradation, heat-treated specimens of rubber wood (Hevea brasiliensis) were exposed to ultraviolet light for 384 h. The color changes in the exposed wood surfaces were analyzed using a colorimeter; the chemical changes were monitored using Fourier-transform infrared spectroscopy (FTIR). The photoweathering performances of rubber wood treated at 155 °C for 2 h, 155 °C for 6 h, and 185 °C for 2 h were similar to that of untreated wood, as the lignin did not undergo profound chemical transformation under mild modification conditions. However, compared to untreated rubber wood, the photoaging performances of rubber wood treated at 185 °C for 6 h and 215 °C for 2 h were notably changed. The transformation process was confirmed by FTIR. A good linear relationship between color change and lignin degradation was observed after mild, but not severe, heat treatment. The concentration of carbonyl groups in the wood specimens generally increased during photoaging, although not all samples showed a good correlation between color change and the concentration of carbonyl groups. Only the photochromic performance of wood changed notably when lignin was extensively modified under severe heat-treatment conditions.

Application and characterization of a novel PVDF-HFP/PVP polymer composite with MoO3 nanowires as a protective coating for wood

“…The exposure of uncoated wood to UV light caused a slight increase of the peak at 2930 cm –1 (C–H asymmetrical and symmetrical stretching 54 ) and a more notable rise of peaks at 1680 cm –1 and 1600 cm –1 , indicating oxidation of lignin 55 and presence of C–C unsaturated linkages in aromatic rings of lignin 56 . An intensified shoulder peak at 1080 cm –1 was attributed to the rearrangements in lignin, specifically the aromatic C–H in plane deformation in guaiacyl units and C–O deformation in primary alcohol 57 .…”

Application and characterization of a novel PVDF-HFP/PVP polymer composite with MoO3 nanowires as a protective coating for wood

“…Another two peaks at 870 cm -1 (indicating γ phase of PVDF-HFP) and 840 cm -1 (indicating β phase of PVDF, -CH 2 -rocking and -CF 2 -stretching) were observed (Dyartanti et al 2018). All these three peaks were promoted with greater lm thickness of C + MoO 3 on wood.The exposure of uncoated wood to UV light caused a slight increase of the peak at 2930 cm -1 (C-H asymmetrical and symmetrical stretching (You Liu et al 2017) and a more notable rise of peaks at 1680 cm -1 and 1600 cm -1 , indicating oxidation of lignin(Li et al 2020) and presence of C-C unsaturated linkages in aromatic rings of lignin(Rosu et al 2010). An intensi ed shoulder peak at 1080 cm -1 was attributed to the rearrangements in lignin, speci cally the aromatic C-H in plane deformation in guaiacyl units and C-O deformation in primary alcohol(Lei et al 2008).…”