FTIR and Raman Spectroscopy of PET
topic
FTIR of PET: characteristic bands at 1715 cm⁻¹ (C=O stretch), 1245 cm⁻¹ (C–O–C stretch), 1018 cm⁻¹ (gauche conformer), 1340 cm⁻¹ (trans conformer CH₂ wagging). Trans/gauche ratio at 1340/1370 cm⁻¹ correlates with crystallinity and orientation. ATR-FTIR gives surface-selective analysis. Raman at 1615 cm⁻¹ (ring mode) and 998 cm⁻¹ (trans conformer) provides crystallinity estimates.
Role
Vibrational spectroscopy provides molecular-level conformational information (trans/gauche ratio) complementary to WAXD crystallinity, and is uniquely suited to surface characterisation and in-situ process monitoring during drawing and texturing.