Surface Characteristic of Wheat Straw Treated with Plasma

Abstract

The waxy wheat straw surface and high SiO2content of wheat straw agrifibres make wheat straw-based panel production much more difficult than traditional wood-based panel manufacture. Plasma surface modification is regarded as one of the cost effective surface treatment techniques for many materials including natural fibers. In this study, plasma technique was employed to treat the surface of wheat straw. After the plasma treatment, the surface properties were then evaluated by determining the contact angles of 3 liquids on the wheat straw surface and by analysis using Fourier Transform Infrared Spectroscopy (FTIR).The results showed that the contact angles of water, glycerol, and UF resin after the plasma treatment decreased by 44.1%, 18.6%, and 24.9%, respectively. In the meantime, –OH, and -C=O groups increased according to the FTIR analysis. The FTIR analysis also indicated a significant SiO2reduction in the plasma treated wheat straw. Obviously, the plasma treatment improved the wettability of wheat straw, increased the numbers of oxygen-containing functional groups, and also removed the weak interface of wheat straw remarkably. By means of the plasma treatment, the internal bond property between modified wheat straw fibers was expected to enhance, and thus some cheaper traditional adhesives such as urea formaldehyde (UF) and phenol formaldehyde (PF) can be used for the wheat straw-based panel production instead of using expensive Diphenylmethane Diisocyanate (MDI).