Crystallization studies of poly (trimethyleneterephthalate) (PTT) by differential scanning calorimetryand ftir spectroscopy
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- Tez No: 710498
- Danışmanlar: PROF. DR. NADARAJAH VESANTHAN
- Tez Türü: Yüksek Lisans
- Konular: Kimya, Chemistry
- Anahtar Kelimeler: Belirtilmemiş.
- Yıl: 2007
- Dil: İngilizce
- Üniversite: Long Island University
- Enstitü: Yurtdışı Enstitü
- Ana Bilim Dalı: Kimya Ana Bilim Dalı
- Bilim Dalı: Belirtilmemiş.
- Sayfa Sayısı: 58
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Özet (Çeviri)
Crystallization of Poly (trimethylene terephthalate) (PTT) by annealing was studied using differential scanning calorimetry (DSC), mid-infrared spectroscopy (MIR) and farinfrared spectroscopy (FIR). Glass transition (Tg), cold crystallization temperature (Tcc), and melting temperatures (Tm) were obtained as a function of annealing temperatures (Ta). The Tg and Tcc tend to disappear when Ta exceeded 80 oC. Two melting transitions, and Tm 2 were observed for those samples annealed at above 120 oC. Crystallinity values was obtained for PTT films annealed inside the DSC before and after cooling to room temperature. Additional crystallinity developed during cooling was attributed to lamella thickening.Digital subtraction of the amorphous contribution from the semicrystalline spectra provided characteristic MIR and FIR spectra of amorphous and crystalline PTT. Normalized absorptions at 1173, and 976 cm-1 were plotted against the crystallinity and demonstrated that they are associated with the amorphous phase. The band at 1358 cm-1 showed an increase in absorbance with increasing annealing temperature. However, no significant change in the absorbances were observed bands at 1504 cm-1 and 793 cm-1 and therefore these bands were used as internal reference bands. It was demonstrated that infrared spectroscopy can be used as a means(deleted) to estimate the trans and gauche conformations. In the FIR region, the bands at 373, 282 and 92 cm-1 were assigned to the crystalline phase, while the bands at 525, 406 and 351 cm-1 were attributed to the amorphous phase. Since a single PTT chain passes through its unit cell, only one lattice vibration, associated with in-phase rotation, is possible. The band at 92 cm-1 is therefore attributed to the PTT crystalline lattice band. Normal coordinate calculations are however required to confirm this assignment. Correlation has been established between the ratio of the 373 cm-1 and the sum of 353 and 331 cm-1 bands and overall PTT crystallinity, as obtained by DSC. This FIR spectroscopic observation suggests that this technique could be used as a complementary technique to monitor the microstructure changes in PTT films. Crystalline gauche and amorphous gauche conformations were determined using combination of MIR spectroscopy and DSC.
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