Abstract:

Two kinds of plant fibers, including natural bamboo fiber made of Neosinocalamus affinis, jute fiber and their single fibers, were analyzed by Fourier Transform infrared (FTIR) spectroscopy and two-dimensional infrared (2D-IR) correlation spectroscopy. Comparing the IR spectra of natural bamboo and jute fibers, we found that the main differences are the peak at around 1 736 cm^-1 related with C=O stretch and the characteristic peaks of lignin. When single fibers were isolated using hydrogen peroxide and glacial acetic acid, the peak at around 1 736 cm^-1 also existed in the IR spectra of jute fiber, but the characteristic peaks of aromatic skeletal vibrations were not observed in both IR spectra of single fibers. In addition, the differences were evident in the maps of synchronous 2D-IR correlation spectra of both fibers. In the region of 1 000~1 250 cm^-1, natural bamboo fiber had eight auto-peaks in diagonal line and the highest auto-peak located at 1 008 cm^-1. But for jute fiber, seven auto-peaks were observed and the highest one was 1 217 cm^-1. And there was one auto-peak situated at 1 726 cm^-1(C=O stretch)between 1 435 and 1 750 cm^-1, which was not observed in natural bamboo fiber. All the auto-peaks were positively correlated. In comparison with the former 2D-IR correlation spectra, the spectra of single bamboo and jute fibers were distinct. It showed that the micro-dynamic changes in the structure of natural bamboo and jute fibers during the min-hearting process were related with the components of fibers. Therefore, this preliminary investigation demonstrated that 2D-IR correlation spectroscopy can become a powerful and new approach to distinguish the natural bamboo fiber from jute fiber.

Key words: 2D-IR correlation spectroscopy, Neosinocalamus affinis, natural bamboo fiber, jute fiber, single fiber