Investigation of the Structural Characteristics of Corn Stalk during Hot-Pressing

Xi Le, Junjian An, Guangyan Zhang, Lei Wang, Jianyun Fan, Peng Wang, Yimin Xie

Abstract


Corn stalk is one of the most abundant agricultural residues in China. In this experiment, corn stalks were hot-pressed to prepare formalin-free particleboard. Milled wood lignin (MWL) samples were isolated from original and hot-pressed corn stalks. To illuminate the self-bonding mechanism of binderless particleboard, the structural characteristics of original corn stalk, hot-pressed corn stalk, and MWL samples were thoroughly investigated by Fourier transform infrared spectroscopy (FT-IR), solid-state cross-polarization magic angle spinning carbon-13 nuclear magnetic resonance spectroscopy (CP-MAS 13C-NMR), X-ray diffraction (XRD), carbon-13 nuclear magnetic resonance spectroscopy (13C-NMR) and gel permeation chromatography(GPC). The degradation of hemicellulose and a portion of amorphous cellulose occurred during hot-pressing. Hot-pressing increased the crystallinity and crystallite size of cellulose in treated corn stalk. The analysis of MWL showed that hot-pressing resulted in corn stalk lignin depolymerization through cleavage of a substantial portion of the β-O-4 linkages in lignin, as well as the decrease of molecular weight of lignin in corn stalk. In addition, acid-catalyzed condensation occurred between lignin and xylose when liberated from hemicellulose. These results demonstrated that condensation between lignin and xylose may contribute to the self-bonding mechanism and improve board properties.

Keywords


Corn stalk; Hot-pressing; Crystallinity; Degradation; Condensation

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Welcome to BioResources! This online, peer-reviewed journal is devoted to the science and engineering of biomaterials and chemicals from lignocellulosic sources for new end uses and new capabilities. The editors of BioResources would be very happy to assist you during the process of submitting or reviewing articles. Please note that logging in is required in order to submit or review articles. Martin A. Hubbe, (919) 513-3022, hubbe@ncsu.edu; Lucian A. Lucia, (919) 515-7707, lucian.lucia@gmail.com URLs: bioresourcesjournal.com; http://ncsu.edu/bioresources ISSN: 1930-2126