Welcome to Chinese Journal of Tropical Crops,

Chinese Journal of Tropical Crops ›› 2019, Vol. 40 ›› Issue (4): 746-752.DOI: 10.3969/j.issn.1000-2561.2019.04.019

• Agricultural Product Processing, Preservation, Storage, Analysis and Detection • Previous Articles     Next Articles

The Characterization of Effects of Thermal Modification on Rubber Wood Color Change Based on FTIR and UV-Vis Analysis

LI Xiaowen,LI Tongtong,LI Guanjun,LI Min,QIN Shaoshan,LU Quanji   

  1. Rubber Research Institute, Chinese Academy of Tropical Agricultural Sciences / State Engineering and Technology Research Center for Key Tropical Crops, Danzhou, Hainan 571737, China
  • Received:2018-07-10 Revised:2018-10-08 Online:2019-04-15 Published:2019-05-21

Abstract:

The color changes of thermally modified rubber wood, which was treated at 155 ℃ and 185 ℃ for 2 and 6 h, and 215 ℃ for 2 h respectively, were analyzed using the CIE L *a *b * color space. Changes in chemical structure of the wood samples were analyzed by UV-visible spectrophotometer (UV-Vis) and Fourier transforms infrared spectroscopy (FTIR). The results showed that the color of rubber wood became orange and then approached dark brown, and the light value L * decreased steadily. The parameter C * increased at the beginning of thermally modified treatment and then went down rapidly. The parameter ΔE * showed a positive correlation with the modification degree, and treatment temperature played a more important role in the change of wood color compared with treatment time. A significant increase emerged in the 350-550 nm in UV-Vis spectra of heat-treated rubber wood above 185 ℃, indicating the generation of chromophoric groups. According to FTIR spectra, the content of lignin increased as hemicellulose and cellulose degraded at high temperature; and the loss of syringyl units or breaking of aliphatic side-chains could be inferred from a shift of maximum absorption from 1507 cm -1 to approximately 1511 cm -1 due to decrease of methoxyl groups. The cleavage of acetyl groups was considered to be detected in FTIR spectra in the samples treated at 155 ℃ for 2 h.

Key words: rubber wood, thermal modification, color, FTIR, UV-Vis