Infrared spectroscopic studies on crystalline phase transition of PVDF and PVDF/hyperbranched polyester blend ultrathin films
| Autor: | D. Manjula Dhevi, Arun Anand Prabu, Kap Jin Kim |
|---|---|
| Rok vydání: | 2018 |
| Předmět: |
Phase transition
Materials science Absorption spectroscopy 02 engineering and technology Thermal treatment 010402 general chemistry 021001 nanoscience & nanotechnology 01 natural sciences Polyvinylidene fluoride Ferroelectricity 0104 chemical sciences Amorphous solid chemistry.chemical_compound Crystallinity chemistry Chemical engineering 0210 nano-technology Spectroscopy |
| Zdroj: | Vibrational Spectroscopy. 94:74-82 |
| ISSN: | 0924-2031 |
| DOI: | 10.1016/j.vibspec.2017.12.003 |
| Popis: | In this study, as cast (AC, at 30 °C) and annealed (AN, at 130 °C, 3 h) samples of polyvinylidene fluoride (PVDF) and PVDF/hyperbranched polyester (HBP) (90/10) blend ultrathin films were subjected to heating-cooling (30 → 210 → 30 °C) cycle, and studied for their changes in crystalline phase transition behavior using in-situ Fourier transform infrared-transmission spectroscopy (FTIR-TS) and grazing incident reflection absorption spectroscopy (FTIR-GIRAS) techniques. Factor analysis was employed to extract the pure crystalline and amorphous spectra as well as the percentage content of ferroelectric crystallinity for both the samples. Irrespective of the thermal treatment (AC or AN) and spectral measurement (FTIR-TS or GIRAS) techniques, neat PVDF sample exhibited irreversible phase transitions during heating-cooling cycle associated with the transformation from ordered β-crystalline (1276 cm−1) into disordered amorphous (1234 cm−1) form. Interestingly, annealed PVDF/HBP blend sample measured using FTIR-GIRAS exhibited reversible crystalline phase transition behavior similar to a ‘dipole memory effect’ even after heating to 210 °C (>Tm) and then cooled to 30 °C. Compared to neat PVDF, higher ferroelectric crystallinity and reversible phase transition in PVDF/HBP blend may be attributed to (i) the existence of H-bonding between HBP (C O and OH groups) and PVDF ( CH2 and CF2) and/or (ii) HBP acting as a nanoparticle in PVDF matrix. |
| Databáze: | OpenAIRE |
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