Study On The Thermal Analysis Of Poly (Trimethylene Terephthalate)

Poly(trimethylene terephthalate) (PTT), is a new promising polymer with potential applications. In this thesis work, the structure and properties of PTT were studied by using Differential Scanning Calorimeter (DSC) and Fourier Transform Infrared Spectrometry (FTIR ) experiments. The thermal analysis through the special FTIR micro-spectroscopy had been applied. In this method, the change of conformational apparent enthalpy AH in phase transitions have been determined by van't Hoff equation at the constant pressure, where ΔH was plotted vs. temperature.Non-isothermal crystallization kinetics of the three aromatic polyesters, poly(ethylene terephthalate)(PET), PTT, and poly(butylenes terephthalate)(PBT), were characterized by using DSC respectively and compared with each other. Based on the Jeziorny, Ozawa, Ziabicki models,the data were analyzed. By combining of the Avrami and Ozawaequations, it was shown that both the Jeziorny and Ozawa models could describe the experimental data successfully. Through the calculation of the Ziabicki's crystallizability parameter G_c, it was found that the crystability of the three polyesters is in the following order: PBT>PTT>PET.When using the thermal analysis of FTIR to examine the physical aged of PTT, it appeared the dual endothermic peaks in the glass transition region. It can be concluded that there were dual amorphous regions with different characteristics in the semicrystalline samples, which one is the free amorphous region and the other is the constrained amorphous region. The local inter-chain cohesion was proved to be the most successful model to explain the experimental results.In situ-scans of semicrystalline PTT, the data were collected over a temperature range of 40-250 °C by PTIR microspectroscopy which was clearly described the phase-transition process at the molecular level. There were two different mechanisms in the crystalline phase and the non-crystalline phase. It was found that the non-crystalline phase starts to melt at 218°C and crystallizes at the same time. The process is end at 238 °C, while the crystalline phase melts at 228 °C with corresponding the peak at 238°C. Usually this process will be end at 242 °C. By comparing the endothermic peaks of the simecrystalline phase, it can be concluded that there were three kinds of melting process in the simecrystalline phase:...