The crystallization of Poly(ethylene terephthalate) studied by thermal analysis and FTIR spectroscopy

Chen, Ziyu (2013). The crystallization of Poly(ethylene terephthalate) studied by thermal analysis and FTIR spectroscopy. University of Birmingham. Ph.D.

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Abstract

This thesis concerns the thermal behaviour and properties, isothermal crystallization kinetics and seeded crystallization study of Poly (ethylene terephthalate) (PET) using thermal analysis Fourier transform infrared (TA-FTIR), two-dimensional infrared correlation spectroscopy (2D-FTIR) and differential scanning calorimetry (DSC).

TA-FTIR has been used to characterize phase transitions by a change in the absorbance or peak position with temperature in thermal cycling. It assigns the phase transition temperature to an individual chain segment and observes two different types of thermal behaviours of the functional groups. FTIR finds out that the carbonyl stretching band has an amorphous band and a crystalline band following by analysis of 2D-FTIR.

The isothermal crystallization kinetics of PET was measured from 230 to 240\(^o\)C by FTIR focusing on carbonyl ester group. The deconvolution of these two overlapping absorption bands analyzes the kinetics of both primary and secondary crystallization by Avrami equations.

Melting behaviour study on DSC observes crystallinity, melting temperature and calculated lamellae thickness of PET increase with the extending time period of isothermal crystallization in secondary process.

Seeded crystallization crystallizes polymers at higher temperatures to produce greater lamellae thicknesses and higher melting temperature and to discuss the effect of this morphology on their mechanical and physical properties.

Type of Work:

Thesis (Doctorates > Ph.D.)

Award Type:

Doctorates > Ph.D.

Supervisor(s):