Effects of wet-pressing induced fiber hornification on hydrogen bonds of cellulose and on properties of eucalyptus paper sheets
2018
Chen, Yangmei | Jiang, Yu | Wan, Jinquan | Wu, Qitang | Wei, Zebin | Ma, Yongwen
The supramolecular structure of eucalyptus pulp cellulose was studied by Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD) and water retention value (WRV) after subjecting the pulp to pressures of 0.1, 0.2, 0.3, 0.4 and 0.5 MPa. It was interpreted from the FTIR spectra of the sheets after pressing that the amount of intermolecular hydrogen bonds (HBᵢₙₜₑᵣ) first increased and then decreased as a function of increasing pressure, while the number of the intramolecular hydrogen bonding (HBᵢₙₜᵣₐ) exhibited an opposite trend. In the pressed fibers, the number of HBᵢₙₜᵣₐ O(6)H· · ·O(3′) increased by 16% compared to the un-pressed fibers, while the number of HBᵢₙₜₑᵣ O(2)H· · ·O(6) and O(3)H· · ·O(5) decreased by 23% at 0.3 MPa. XRD analysis showed that the crystallite size corresponding to the diffraction peaks for (002) lattice planes and the crystallinity of eucalyptus fibers were the lowest at a pressure of 0.3 MPa. Pressing produced an irreversible reduction of fiber pore volume, which was manifested by reduced WRV data.
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