Poly(ethylene succinate) (PES), poly(trimethylene succinate) (PTS) and their copolyesters (PETSAs) with various compositions were used to investigate the structure-property relationship. The results of intrinsic viscosity and GPC have proven successful in preparing high molecular weight polyesters. The chemical compositions and the sequence distribution of co-monomers in the copolyesters were determined by NMR spectroscope. The distributions of ES unit and TS unit were found to be random. Their thermal properties were characterized using differential scanning calorimeter (DSC). The thermal stability of polyesters was analyzed by thermogravimeter (TGA) and polarized light microscope (PLM) under nitrogen. The results of TGA show that all of the samples have similar thermal stability (Tstart : 246¡Ó3 ¢XC), but the thermal
degradation temperature of PES and PETSA(95/05) are 213 and 200 ¢XC, respectively,
estimated from the isothermal growth rates after pre-melting at various temperatures.
The degradation temperature analyzed by PLM is more sensitive than that obtained
from TGA. The incorporation of 5 mol% of TS units into PES significantly reduces
the thermal stability of PES. In addition, wide-angle X-ray diffractograms (WAXD)
were obtained for polyesters which were crystallized isothermally at a temperature
5~10 ¢XC below their melting temperatures. The results of WAXD and DSC indicate
that the incorporation of TS units into PES significantly inhibit the crystallization
behavior of PES.
In the second part of this study, PES and PETSA(95/05) were studied in detail.
The crystallization kinetics and the melting behavior were investigated by using DSC
in both conventional mode and modulated mode (TMDSC). The reversing, total, and
non-reversing heat flow curves were analyzed. The Hoffman-Weeks plots gave an
equilibrium melting temperature of 112.7 and 108.3 ¢XC for PES and PETSA(95/05),
XI
respectively. Only one crystal form was found from WAXD for specimens crystallized
isothermally at various temperatures. Based on the WAXD patterns, DSC and
TMDSC thermograms, multiple endothermic melting peaks can be explained by two
mechanisms, melting-recrystallization-remelting and dual morphologies. PLM was
used to study the growth rates and morphology of the spherulites. The growth rates
measured in isothermal conditions were very well comparable with those measured by
the non- isothermal procedure. In addition, the temperature range of growth rates
detected by the non- isothermal procedure is wider than that by the isothermal method,
which is time consuming. The regime II®III transition of PES was estimated at ~ 71
¢XC which is very close to the literature values, and that of PETSA(95/05) was found at
~ 65 ¢XC.
| Identifer | oai:union.ndltd.org:NSYSU/oai:NSYSU:etd-0703106-172831 |
| Date | 03 July 2006 |
| Creators | Chang, Wei-che |
| Contributors | Shih-jung Bai, Ming Chen, Chi Wang |
| Publisher | NSYSU |
| Source Sets | NSYSU Electronic Thesis and Dissertation Archive |
| Language | Cholon |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://etd.lib.nsysu.edu.tw/ETD-db/ETD-search/view_etd?URN=etd-0703106-172831 |
| Rights | withheld, Copyright information available at source archive |
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