Mechanical Function of Lignin and Hemicelluloses in Wood Cell Wall Revealed with Microtension of Single Wood Fiber

Abstract

Chinese Fir wood (Cunninghamia lanceolata (Lamb.) Hook) was subjected to extraction treatments with sodium chlorite (NaClO 2 ) for delignification, as well as with sodium hydroxide (NaOH) at different concentrations for extraction of hemicelluloses. The wood was examined using a Fourier Transform Infrared (FT-IR) spectrometer and microtension technique to track changes in the chemical and the micromechanical properties of the cell wall. The results of the microtensile tests indicated that the hemicelluloses caused more damage to the mechanical properties of the cell wall than lignin. The micromechanical properties that occurred with degradation of chemical components underlined the key role of hemicelluloses in maintaining the integrity of the cell wall.

Effects of Chemical Extraction Treatments on Nano-scale Mechanical Properties of the Wood Cell Wall

“…The indentation moduli of the cell wall after delignification and successive alkali treatment were 6.4% and 14.8% lower than that of the native cell wall, respectively. A similar trend in the mechanical properties with microtension was reported in a previous study (Zhang et al 2013).…”

Contributions of Basic Chemical Components to the Mechanical Behavior of Wood Fiber Cell Walls as Evaluated by Nanoindentation

“…It is evident that there was little to no remaining lignin in sample D, i.e., the lignin in the wood cell wall had been removed by the NaClO2/acetic acid. During all chemical extractions, slight modifications in the peaks at 1368 and 897 cm -1 illustrated that the cellulose was the least changeable wood component, relative to the treatments employed in the present study (Zhang et al 2013). Figure 5a shows the X-ray diffractograms of the control, benzene-ethanol extracted, alkaline-treated, and delignified wood samples.…”

“…At the end of the load-holding period, the creep compliance, J(30), increased by 38.7%, 41.8%, 50.3%, and 60.4% for sample A, sample B, sample C, and sample D, respectively, meaning that the fiber cell walls deformed more under the constant load after chemical extraction, especially with the alkaline and delignification treatments. The degradation of hemicelluloses and lignin in the cell walls might also weaken the structural continuity and reduced the resistance of the wood cell walls to creep (Zhang et al 2013). The benefit of the four-parameter Burger's model is that the fitting parameters can be interpreted physically as an instantaneous elastic deformation, followed by a visco-elastic deformation and viscous deformations (Fig.…”

Comparison between degradation capabilities of the white rot fungi Pleurotus ostreatus and Trametes versicolor in beech wood

“…There are many well-defined peaks in the fingerprint region of 1800e600 cm À1 . The assigned peaks in the region mentioned are unconjugated C]O matching xylan at 1735 cm À1 which is increased in wood decayed by both fungi (Mohebby, 2005;Zhang et al, 2013). The increase of the C]O might be related to changes in wood lignin and cleaving aromatic skeletal structures from hemicelluloses due to enzymatic attacks.…”

“…There was also a new peak which was appeared at 1596 cm À1 . This peak is assigned for conjugated CeO stretching (Mohebby, 2005;Zhang et al, 2013). It is an indication of cleavage in lignin structure (Mohebby, 2005).…”