Preparation and characterization of xylan derivatives and their blends

Authors: Cheng, Huai; Ford, Catrina; KOLPAK, FRANCIS - Ashland-Us; WU, QINGLIN - LSU Agcenter

Submitted to: Journal of Polymers and the Environment
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/16/2018
Publication Date: 10/1/2018
Citation: Cheng, H.N., Ford, C., Kolpak, F.J., Wu, Q. 2018. Preparation and characterization of xylan derivatives and their blends. Journal of Polymers and the Environment. 26:4114-4123. https://doi.org/10.1007/s10924-018-1279-3.
DOI: https://doi.org/10.1007/s10924-018-1279-3

Interpretive Summary: One of the goals of our work is to upgrade the value of agricultural materials, particularly those that are under-utilized. Xylan is a commonly found agro-based material, but few xylan products have appeared in the marketplace. In this work, we have made cationic and anionic derivatives of xylan and characterized them with NMR, IR, SEC, TGA, DSC, and rheology. When cationic and anionic xylan samples were combined in solution, they formed a polyelectrolyte complex and became partly insoluble. This blend of cationic xylan and anionic xylan may have useful properties in product applications. For example, the blend of these two xylan derivatives was found to enhance the dry strength of paper.

Technical Abstract: Although hemicellulose is found widely in nature, it is currently under-utilized as a raw material for commercial applications. It would be desirable to find new uses for hemicellulose in order to add value to this agro-based material. A common type of hemicellulose is xylan, which is found in a number of wood species and in cotton. In this work we prepared cationic and anionic xylan derivatives and characterized them by 13C NMR, FT-IR, size exclusion chromatography, thermal analysis, and rheology. In particular, the 13C NMR spectra of the polymers were fully assigned with the help of samples with different degrees of substitution. Size exclusion chromatography indicated that the beechwood xylan showed a bimodal molecular weight distribution, but with derivatization the distribution tended to become monomodal. Thermal analysis and rheology studies did not uncover any surprises; the solution of xylan and its derivatives exhibited mostly Newtonian behavior. The blends of CMX and QAX produced a precipitate at almost all ratios, indicating the formation of a polyelectrolyte complex. When cationic and anionic xylan samples were added together to paper, the paper dry strength increased. Thus, the combination of cationic/anionic xylan may potentially be useful in commercial applications.