Analysis of Among-Species Variability in Wood Fiber Surface Using DRIFTS and XPS: Effects on Esterification Efficiency

Abstract

Variability in the chemical composition of surface properties of various wood fibers (eastern white cedar, jack pine, black spruce, and bark) was investigated using diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) and X-ray photoelectron spectroscopy (XPS). Both DRIFTS and XPS showed high variability in fiber surface composition between species and between fiber types (sapwood, heartwood, and bark). Fiber surface was modified by esterification reaction using a maleic anhydride polyethylene (MAPE) treatment. DRIFTS failed to assess surface modification, whereas XPS results showed that MAPE treatment increased the surface hydrocarbon concentration of jack pine wood fiber, indicated by a decrease in oxygen-carbon ratio and an increase in relative intensity of the C1 component in the C1s signal. Lignin concentration variability on the fiber surface was determined as the major factor that prevents esterification from taking place.

Surface properties of methyl methacrylate hardened hybrid poplar wood

“…The spectra of the untreated wood particles showed the presence of a typical band observed in wood. [24][25][26] A broad stretching band for intermolecular bonded hydroxyl groups (OH) was observed at 3400 cm…”

“…26,28,29 The medium intensity bands around 1457, 1424, and 1373 cm À1 were associated with methylene deformation and methyl asymmetric and methyl symmetrical vibrations. [24][25][26] The bands appearing at 1271 cm À1 were due to either a carbon single-bonded oxygen stretching vibration or an interaction vibration between carbon single-bonded oxygen stretching and in-plane carbon single-bonded hydroxyl bending in carboxylic acids. 30 The band at 1158 cm À1 may have arisen from the asymmetric stretching of CAOAC in the cellulose and hemicelluloses 26,31 or from saturated fatty acid ester carbon single-bonded oxygen stretching in association with the ester carbonyl.…”

“…A broad, medium intensity ester carbonyl vibration appearing at 1735 cm À1 was presumed to emanate from the carbonyl (C¼ ¼O) stretching of acetyl groups in hemicelluloses and carbonyl aldehyde in lignin and extractives. 24,26,27 The bands around 1605 and 1510 cm À1 were associated with the aromatic C¼ ¼C skeletal vibrations associated with the lignin. 26,28,29 The medium intensity bands around 1457, 1424, and 1373 cm À1 were associated with methylene deformation and methyl asymmetric and methyl symmetrical vibrations.…”

“…24,26,27 The bands around 1605 and 1510 cm À1 were associated with the aromatic C¼ ¼C skeletal vibrations associated with the lignin. 26,28,29 The medium intensity bands around 1457, 1424, and 1373 cm À1 were associated with methylene deformation and methyl asymmetric and methyl symmetrical vibrations. [24][25][26] The bands appearing at 1271 cm À1 were due to either a carbon single-bonded oxygen stretching vibration or an interaction vibration between carbon single-bonded oxygen stretching and in-plane carbon single-bonded hydroxyl bending in carboxylic acids.…”

“…[24][25][26] The bands appearing at 1271 cm À1 were due to either a carbon single-bonded oxygen stretching vibration or an interaction vibration between carbon single-bonded oxygen stretching and in-plane carbon single-bonded hydroxyl bending in carboxylic acids. 30 The band at 1158 cm À1 may have arisen from the asymmetric stretching of CAOAC in the cellulose and hemicelluloses 26,31 or from saturated fatty acid ester carbon single-bonded oxygen stretching in association with the ester carbonyl. 26,31 Strongintensity bands at 1059 and 1036 cm À1 were essentially in the positions corresponding to those observed in the IR spectra of single cotton fibers.…”