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Title: Spectroscopic analysis of the role of extractives on heat-induced discoloration of black locust (Robinia pseudoacacia)

Source: Wood Material Science & Engineering 0.0:1-8; 2012.

Author(s)Chen, Yao; Fan, Yongming; Gao, Jianmin; Tshabalala, Mandla A.; Stark, Nicole M.

Publication Year: 2012  View PDF »

Category: Journal Articles
Associated Research Project(s):   FPL-4706-2B   FPL-4707-2A

Abstract: To investigate the role of extractives on heat-induced discoloration of wood, samples of black locust (Robinia pseudoacacia) wood flour were extracted with various solvents prior to heat-treatment. Analysis of their color parameters and chromophoric structures showed that the chroma value of the unextracted sample decreased while that of the extracted sample increased after heat-treatment. Both samples showed broad diffuse reflectance UV-Vis (DRUV) absorption bands with maxima around 360-380 nm after heat-treatment due to the formation of conjugated double bonds, carbonyl functionalities, and quinoid structures. Compared with the unextracted sample, the dominant chromaticity of the extracted samples hypochromatically shifted and the peak became narrower. This result showed that extractives contribute mostly to the reduction in the light reflection on heat-treated wood. In addition to extractives, lignin and hemicellulose also contributed to the formation of color substances upon heat-treatment. The increase in C3/C2 ratio in X-ray photoelectron spectroscopy (XPS) spectra signified the oxidation reactions in the heating process. The increase in O1/O2 for extracted sample after heat-treatment and changes in DRUVand Fourier transform infrared spectroscopy (FTIR) spectra support the hypothesis that discoloration can also arise from the degradation of hemicellulose and the condensation reactions of lignin.

Keywords: color space; discoloration; diffuse reflectance UV-Vis (DRUV); attenuated total reflectance-Fourier transform infrared (ATR-FTIR); heat treatment; X-ray photoelectron spectroscopy (XPS)

Publication Review Process: Formally Refereed

File size: 585 kb(s)

Date posted: 09/27/2012

This publication is also viewable on Treesearch:  view
RITS Product ID: 61846
Current FPL Scientists associated with this product (listed alphabetically)
Stark, Nicole M.
Research Chemical Engineer
Tshabalala, Mandla A.
Research Chemist

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