Table 3.
Description of vibrations in FTIR spectra of S-TPU(PCL)0.9/1.1.
| Wavelength [cm−1] | Band | Description |
|---|---|---|
| 3330–3318w | νNH | N-H stretching of urethane bond. Free and hydrogen bonded NH. |
| 2917w, 2850w | νCH2 | Asymmetric and symmetric stretching C-H vibrations occurring in the aliphatic chains. |
| 1717s | νC=O | Stretching vibration of carbonyl group of PCL part. |
| 1686vs, 1660w | νC=O | Stretching vibration of carbonyl group occurring in the urethane bond; non-hydrogen bonded and strongly hydrogen bonded urethane group. |
| 1542m | δNH | N-H deformation of urethane bond (bending vibration). |
| 1464m | δCH2 | C-H deformation (scissoring in plane). |
| 1223s | νN–C | Stretching vibration (urethane bonding). |
| 1160s | νC–O | Stretching vibration of ester (PCL part). |
| 1065m, 1038m | νC–O | Stretching vibration of C-O occurring in the urethane bond. |
| 730v | γC–C | Skeletal vibrations of alkaline carbon chain (-C-Cn-, n>4) present in HDI/ or PCL structure. |
| 640m | δN–H | Wide spectrum of N-H wagging, out of plane. |
vw—very weak, w—weak, m—medium, s—strong, vs—very strong, v—variable.