Table 1.
Absorption signals of Fourier transform infrared spectroscopy for the spectrum of hemp fibers.
| Name of the Function Group | Wavenumber [cm−1] |
Bibliographic |
|---|---|---|
| C-OH out-of-plane bending vibrations; C-C | 557 | [46] |
| Stretch vibrations of the glucose ring; C–H stretching vibrations outside the plane of the aromatic ring |
895 | [22,23] |
| -OH; -COO | 900–1200 | [47] |
| CO-O-CO | 1000–1100 | [48] |
| C-O stretching vibrations; deformation of the C-H aromatic plane | 1030–1058 | [49,50] |
| The absorption band of hydroxyl compounds -OH | 1100 | [51,52] |
| C-O stretching vibrations; asymmetric bridge C-O-C stretching vibrations | 1158 | [52,53] |
| C-O; C=O; C-C-; COOH | 1100–1300 | [54] |
| Acyl-oxygen CO-OR stretching vibrations in hemicelluloses; -CH3 | 1245 | [50] |
| C-H deformation vibrations; -OH bending vibrations | 1325 | [51] |
| C-H bending vibrations related to the structure of cellulose and hemicellulose | 1369 | [53,55] |
| CH2 stretching vibrations related to the cellulose structure, vibrations of the bonds of the aromatic backbone | 1425–1426 | [52,53,56,57] |
| CH deformation vibrations; asymmetric bending vibrations from -CH2 and -CH3 groups | 1426–1463 | [46] |
| C=C stretching vibrations in aromatic structures | 1508 | [51] |
| C=C stretching of the aromatic ring | 1550 | [45] |
| C=C unsaturated bonds; | 1592 | [51] |
| COO− (pectin) | 1650 | [45] |
| -OH from absorbed water; C=C | 1653 | [50,51,56,58] |
| C=O stretching vibrations in uncoupled ketones and free aldehydes | 1736; 1718 | [55,56,57,59,60] |
| CH stretching vibrations in methyl and methylene groups | 2896 | [53,55,61] |
| -OH stretching vibrations (hydrogen bonds) | 3331 | [53,62] |