Mid-infrared spectroscopy and colorimetry of curupixá wood: artificial weathering along with finishing products

Abstract

This study investigates the changes in color and in the chemical structures of the surface of curupixá wood (Micropholis sp.), which was exposed to artificial weathering with two wood finishing products. We treated the sample surfaces with varnish and stain, and then we set them to artificial weathering for 700 hours, in accordance with ASTM G154 (2006). Our team used The Fourier Transform Mean Infrared (FT-MIR) and the CIELAB (1976) system in order to outline changes in the chemical and colorimetric structure of the wood surface, respectively. The color of curupixá wood got darker after applying finishing products. The color variation following the weathering process was appreciable in the control sample and very appreciable in the treated wood sample. The analysis of medium infrared spectroscopy demonstrated the depolymerization of lignin accompanied by the formation of carbonyls in all cases. In addition, mid-infrared displayed a concentration drop due to the heavy metal leaching. These ocurrences reveal degradation in the structural chemical components of the wood, and that the finishing products did not affect the weathering process at all.

Keywords:
Wood surface; Photodegradation; Varnish; Stain