TABLE 5.
Wave number assignments of FTIR spectra of PSPs with different sizes.
| Group (cm−1) | Hydroxyl absorption | C-H key stretching vibration frequency | Carbonyl | Amide I with C-O stretching vibration | C-N stretching vibration, N-H bending vibration | C-O stretching vibration or phosphoric acid carrier absorption |
|---|---|---|---|---|---|---|
| α | 3403.1 | 2927.8 | 1736.9 | 1610.2 | 1244.9 | 1053.0 |
| β | 3410.5 | 2924.1 | 1735.1 | 1638.2 | 1246.8 | 1054.8 |
| γ | 3403.1 | 2926.0 | 1736.9 | 1628.8 | 1252.4 | 1053.0 |
| δ | 3395.6 | 2926.0 | 1735.1 | 1636.3 | 1254.2 | 1071.6 |
| ε | 3403.1 | 2926.0 | 1736.9 | 1610.2 | 1246.8 | 1034.3 |