Poly(ethylene succinate) (PES), poly(trimethylene succinate) (PTS) and their copolyesters with various compositions were synthesized through a direct polycondensation reaction with titanium tetraisopropoxide used as the catalyst. Results obtained from intrinsic viscosity and gel permeation chromatography (GPC) studies have significantly contributed to the preparation of polyesters with high molecular weight. Compositions and sequence distributions of the synthesized copolyesters were determined by analyzing the spectra of 1H NMR and 13C NMR. According to those results, the sequence distributions of ethylene succinate (ES) units and trimethylene succinate (TS) units were found to be random. Thermal properties were then characterized using differential scanning calorimeter (DSC) and thermogravimetric analyzer (TGA). All copolymers exhibited a single glass transition temperature (Tg). These polyesters did not significantly differ in thermal stability. Next, thermal stability was estimated using polarized light microscopy (PLM). Isothermal growth rates for polyesters were observed after pre-melting at various temperatures. The thermal degradation temperature (Td) was estimated, at which the growth rate for polyesters increased abruptly. The Td value of PES and PETSA 95/05 was found to be 213 and 200 ¢XC, respectively, which was 35−45 ¢XC lower than that determined by TGA. Wide-angle X-ray diffractograms (WAXDs) were obtained for polyesters that were crystallized isothermally at a temperature 5−10 ¢XC below their melting temperatures. Only the crystal form of PES was appeared in the diffractograms of PES-rich copolyesters. The TS units in polyesters may be excluded and located in the amorphous part of polyesters. WAXD results indicate that incorporating TS units into PES could significantly inhibit the crystallization behavior of the latter. Additionally, dynamic mechanical properties of moldable polyesters were investigated using a Rheometer operated at 1 Hz. Below Tg, incorporating TS units into PES led to a decline in the storage modulus, while above Tg, the effect of crystallinity on the storage modulus could be found. The sphreulite growth rates for crystallizable polyesters were measured by PLM. The growth rate of polyesters decreased with an increasing moiety of TS units. The regime II¡÷III transition of PES was estimated to occur at ca. 71 ¢XC, which is extremely close to values in the literature. The regime transition of PETSA95/05 and PETSA 80/20 was found to be 65.0 ¢XC and 51.4 ¢XC, respectively. A dynamic crystallization experiment was performed by PLM and compared with time consuming isothermal experiments. Above data closely corresponded to those data points determined in the isothermal experiments. Results of the regime analysis for the continuous data of polyesters closely resembled those of isothermal experiments. The maximum growth rate was formulated in Arrhenius and WLF expressions for the molecular transport term. A master curve of the crystal growth rate for PES was constructed based on the continuous data of PES. Plotting the reduced growth rates after normalization against the reduced temperatures revealed a universal master curve for PES and two PES-rich copolyesters. Finally, the lateral surface free energy, fold surface free energy and work for chain folding of polyesters were evaluated based on kinetic analysis. According to those results, the works for chain folding decreased with an increasing moiety of TS units.

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.