PET/PTT共聚酯在熱差分析儀(Differential Scanning Calorimetry, DSC)中，以五種不同的冷卻速率(1~20oC/mim)來進行非等溫結晶。然後利用Ozawa與修改過的Avrami方程式分析共聚酯的非等溫結晶動力學。結果發現，除了組成為66.3% trimethylene- (TT) and 33.7 % ethylene- terephthalates (ET)之共聚酯能夠符合Ozawa方程式。對於大部分共聚酯而言，無法利用Ozawa方程式分析來動力學。這是由於方程式本身的假設有不正確之處，例如不考慮二級結晶對非等溫結晶動力所造成的影響。若是以修改過的Avrami方程式分析的話，得知Avrami指數在2.43到4.67範圍之間，且與共聚酯的組成有關。此結果指出PET/PTT 共聚酯在非等溫情況下，一級結晶為異質成核，三維空間球晶成長機構。不同的是，TT或ET 含量低於10%以下共聚酯，我們發現到融熔溫度是關鍵的因素來決定是否可利用Ozawa方程式來分析非等溫結晶動力學。
在非等溫結晶中，不論共聚酯組成與冷卻速率為何，都只出現單一放熱峰。由此可判定在冷卻過程中，只產生單一型分佈球晶尺寸。非等溫結晶過後，利用Temperature Modulated DSC (TMDSC)中的傳統(conventional)與調制(modulated)模式，來探討樣品的熔融行為。在兩種模式中皆可觀察出多重融熔峰。這些共聚酯的廣角X光繞射圖(Wide-angle X-ray Diffraction, WAXD)顯示出當結晶溫度增加時，繞射峰的強度會隨著增強，但所在之位置並不會有明顯的改變。它指出多重融熔峰並不是由於擁有不同的結晶結構的晶體發生融熔所造成的。因此可利用熔融再結晶模型來合理地解釋共聚酯的融熔行為。從TMDSC的可逆熱流以及不可逆熱流中，也能進一步地證實融熔-再結晶-再融熔的現象。此外，對於高TT含量之共聚酯，在可逆熱流上發現最高融熔溫度的一根小吸熱峰。它可合理地相信這是由於升溫過程中，在區域I所形成的結晶融熔所造成。
DSC與WAXD用來研究PET/PTT共聚酯的共結晶(Cocrystallization)行為。在DSC熱曲線上，各種組成的共聚酯都可出現明顯的吸熱峰。含有50% ET的共聚酯具有最低融熔溫度。依照繞射峰位置，這些共聚酯的WAXD 圖譜可區分成二大類，也就是PET與PTT型態的球晶。PET與PTT型態間的結晶構造的轉移(Crystal transition)發生在由熔融溫度的變化量與組成所決定的共熔組成(50 % ET 和TT)附近。此外，共熔組成的共聚酯，在fiber diagram與WAXD圖譜顯示出它具有不同結晶結構。這些結果指出PET/PTT共聚酯的共結晶行為是等向雙型態的(Isodimorphic)。

Non-isothermal crystallization of the PET/PTT copolyesters was studied at five different cooling rates over 1-20oC/min by means of differential scanning calorimetry (DSC). Both the Ozawa equation and the modified Avrami equation have been used to analyze the crystallization kinetics. The non-isothermal kinetics of most copolymers cannot be described by the Ozawa analysis, except the copolyester with a composition of 66.3% trimethylene- (TT) and 33.7 %ethylene- terephthalates (ET). It may be due to the inaccuracy of the Ozawa assumptions, such as the secondary crystallization is neglected. From the kinetic analysis using the modified Avrami equation, the Avrami exponents, n, were found to be in the range of 2.43-4.67 that are dependent on the composition of the copolyesters. The results indicated that the primary crystallization of the PET/PTT copolymers followed a heterogeneous nucleation and a spherulitic growth mechanism during the non-isothermal crystallization. In the cases of the copolyesters with either TT or ET less than 10%, we found the molten temperature is a key factor to decide whether the Ozawa equation can be succeeded in analyzing the dynamic crystallization.
For the non-isothermal crystallization, a single exothermic peak was detected in each DSC curve regardless of the composition and the cooling rate. It indicated that a single-mode distribution of the crystallite sizes was formed during the cooling process. After the non-isothermal crystallization, the melting behavior of the specimens was monitored by temperature modulated DSC (TMDSC) in the conventional mode and the modulated mode. Multiple endothermic peaks were observed in both modes. The wide-angle X-ray diffraction (WAXD) patterns of these copolymers showed that the peak height became sharper and sharper as the crystallization temperature increased, but the position of the diffraction peaks did not change apparently. It indicated that the multiple melting behaviors did not originate from the melting of the crystals with different structures. The melting behavior of these PET/PTT copolyesters can be explained logically by using the melt-recrystallization model. From the reversing and non-reversing signals of TMDSC, the melting-recrystallization-remelting phenomena were further verified. In addition, a small endothermic peak was found at the highest melting temperature in the reversing thermogram for TT-enriched copolyesters. It is reasonably to believe that this endotherm is attributed to the melting of the crystals that are formed in regime I during the heating scan.
The cocrystallization of the PET/PTT copolyesters was studied using DSC and WAXD. A clear endothermic peak in the DSC thermogram was detected over the entire range of copolymer composition. A minimum melting temperature was found for the copolyester with 50% ET. The WAXD patterns of these copolymers can be divided into two groups with sharp diffraction peaks, i.e., PET type and PTT type crystals. The transition of crystal structure between PET type and PTT type occurred around the eutectic composition (50 % ET and TT), determined from the variation of the melting temperature with the composition. In addition, the fiber diagram and the WAXD pattern of the copolyester with the eutectic composition showed a different crystalline structure. These results indicated that the cocrystallization behavior of the PET/PTT copolyesters was isodimorphic.

Contents
摘要 1
Abstract 2
1. Introduction 4
1.1. Objectives 7
1.2. Flow Chart 7
2. Paper review and theoretical background 8
2.1. Non-isothermal crystallization Kinetics 8
2.2. Thermal analysis 12
2.2.1. Differential scanning calorimeter (DSC) 12
2.2.2. Temperature modulated differential scanning calorimeter (TMDSC) 12
2.2.3. Interpretation of TMDSC 13
2.3. Multiple endotherm behaviors 14
2.4. Cocrystallization behavior of copolymer 15
2.5. Crystal structures of polyester 16
3. Experimental 19
3.1. Materials 19
3.2. Instruments 19
3.3. Sample preparation 19
3.4. Temperature Modulated Differential Scanning Calorimeter (TMDSC) 20
3.4.1. Non-isothermal crystallization 20
3.4.2. Melting behaviors 20
3.5. Differential scanning calorimeter (DSC) 21
3.5.1. Specimens preparation for WAXD measurement 21
3.5.2. Finding Regime I→II transition temperature (TI→II) 21
3.6. Wide-angle X-ray diffraction (WAXD) measurement 21
3.7. High Temperature Wide-angle X-ray diffraction (HTWAXD) measurement 22
3.8. Uniaxially Oriented Samples Preparation 22
3.9. Fiber pattern measurement 22
4. Results and Discussion 23
4.1 Regime I→II transition temperature 23
4.2 Non-isothermal crystallization 24
4.2.1 Ozawa analysis 25
4.2.2 Analysis using modified Avrami equation 26
4.2.3 Effect of the molten temperature on the Ozawa analysis 28
4.3 Melting Behaviors 30
4.3.1 Determining the mechanism of multiple endothermic peaks 30
4.3.2 Multiple endothermic peaks of the C2 PET/PTT copolyester 31
4.3.3 Multiple endothermic peaks of the C3 PET/PTT copolyester 35
4.3.4 Multiple endothermic peaks of the C4 PET/PTT copolyester 38
4.3.5 Multiple endothermic peaks of the C6 PET/PTT copolyester 41
4.3.6 Multiple endothermic peaks of the C7 PET/PTT copolyester 43
4.3.7 Multiple endothermic peaks of the C8 PET/PTT copolyester 45
4.3.8 Summary 47
4.4 Cocrystallization behavior of PET/PTT copolyesters 48
4.5 Crystal structure of C5 PET/PTT copolyester 50
5. Conclusion 52
References 55

List of Tables

Table 1. The compositions, the randomness parameter (B) and the average- number sequence lengths of PT and ET units. 60
Table 2. Equilibrium melting temperature and melting condition of the PET/PTT copolyester. 60
Table 3. Nonisothermal Crystallization and Melting Data of Poly[(ethylene)-co-(trimethylene terephthalate)]s 61
Table 4. Ozawa exponent m and Cooling function F(T) of C2 copolyester at different temperatures. (Melting condition: 245 oC, hold 5 min) 63
Table 5. Ozawa exponent m and Cooling function F(T) of C2 copolyester at different temperatures. (Melting condition: 240oC, hold 5 min) 63
Table 6. Ozawa exponent m and Cooling function F(T) of C3 copolyester at different temperatures. (Melting condition: 215oC, hold 5 min) 63
Table 7. Ozawa exponent m and Cooling function F(T) of C8 copolyester at different temperatures. (Melting condition: 270oC, hold 5 min) 63
Table 8. Avrami parameters of Poly[(ethylene)-co-(trimethylene terephthalate)]s 64
Table 9. TMDSC data of C2 copolyester that crystallized nonisothermally from the molten state at different cooling rate, at a heating rate of 2 oC/min with a period of 40 s (all temperature in oC) 65
Table 10. TMDSC (2 oC/min) data for C2 copolyester after crystallized nonisothermally from the molten state at different cooling rate including heats of melting and crystallization (all temperature in oC ) 65
Table 11. TMDSC data of C3 copolyester that crystallized nonisothermally from the molten state at different cooling rate, at a heating rate of 3 oC/min with a period of 40 s. All temperature in oC. 66
Table 12. TMDSC data for C3 copolyester after crystallized nonisothermally from the molten state at different cooling rate including heats of melting and crystallization. 66
Table 13. TMDSC data of C4 copolyester that crystallized nonisothermally from the molten state at different cooling rate, at a heating rate of 3 oC/min with a period of 40 s. All temperature in oC. 67
Table 14. TMDSC data of C4 copolyester that crystallized nonisothermally from the molten state at different cooling rate, at a heating rate of 3 oC/min with a period of 40 s, including heats of melting and crystallization. 67
Table 15. TMDSC data of C6 copolyester that crystallized nonisothermally from the molten state at different cooling rate, at a heating rate of 3oC/min with a period of 40 s. All temperature in oC. 68
Table 16. TMDSC data of C6 copolyester that crystallized nonisothermally from the molten state at different cooling rate, at a heating rate of 3 oC/min with a period of 40 s, including heats of melting and crystallization. 68
Table 17. TMDSC data of C7 copolyester that crystallized nonisothermally from the molten state at different cooling rate, at a heating rate of 3 oC/min with a period of 40 s. All temperature in oC . 69
Table 18. TMDSC data of C7 copolyester that crystallized nonisothermally from the molten state at different cooling rate, at a heating rate of 3oC/min with a period of 40 s, including heats of melting and crystallization. 69
Table 19. TMDSC data of C8 copolyester that crystallized nonisothermally from the molten state at different cooling rate, at a heating rate of 3 oC/min with a period of 40 s. All temperature in oC. 70
Table 20. TMDSC data of C8 copolyester that crystallized nonisothermally from the molten state at different cooling rate, at a heating rate of 3oC/min with a period of 40 sec, including heats of melting and crystallization. 70
Table 21. Crystallographic Data for PET and PTT. 71
Table 22. Avrami parameters of Poly[(ethylene)-co-(trimethylene terephthalate)]s 71
Table 23.The melting temperature(Tm) and annealing temperature (Ta) for uniaxially oriented copolyester preparation. 71
Table 24. Observed and calculated X-ray spacings of PTT, PET and their copolyesters 72

List of Figures

Figure 1- 1 Chemical structure of PET 4
Figure 1- 2 Chemical structure of PTT 5
Figure 1- 3 Schematic plot of the experimental flow chart 7
Figure 2- 1 Typical Ozawa plots 17
Figure 2- 2 Typical modified Avrami plots 18
Figure 2- 3 Typical multiple endothermic peaks on heating process . 18
Figure 1. DSC thermograms at a heating rate of 80oC/min for C2 copolyester specimens isothermally crystallized at various temperatures indicated in the figure. 73
Figure 2. DSC thermograms at a heating rate of 80oC/min for C2 copolyester specimens isothermally crystallized at various temperatures indicated in the figure. 73
Figure 3. DSC nonisothermal crystallization curves of C2 copolyester at various cooling rates. (Sample was preheated from room temperature up to 252oC at 20oC/min and maintained at 252oC for 5 min). 74
Figure 4. Plots of relative crystallinity XT versus crystallization temperature for C2 copolyester crystallized nonisothermally at various cooling rates. 74
Figure 5. Plots of relative crystallinity XT versus crystallization time for C2 copolyester crystallized nonisothermally at various cooling rates. 75
Figure 6. Plots of log[-ln(1- XT)] versus logR at indicated temperatures for C2 copolyester crystallized nonisothermally at various cooling rates. (Sample was preheated from room temperature up to 252 oC at 20oC/min and maintained at 252oC for 5 min). 75
Figure 7. Plots of log[-ln(1- XT)] versus logR at indicated temperatures for C2 copolyester crystallized nonisothermally at various cooling rates. (Sample was preheated from room temperature up to 245oC at 20oC/min and maintained at 245oC for 5 min). 76
Figure 8. Plots of log[-ln(1- XT)] versus logR at indicated temperatures for C2 copolyester crystallized nonisothermally at various cooling rates. (Sample was preheated from room temperature up to 240oC at 20oC/min and maintained at 240oC for 5 min). 76
Figure 9. Avrami plots of relative crystallinity XT for C2 copolyester crystallized nonisothermally at various cooling rates. 77
Figure 10. DSC thermograms at a heating rate of 50oC/min. for the melt-crystallized C2 samples cooled from melting state at various cooling rates indicated in the figure. 77
Figure 11. Total heat flow ofTMDSC data at a heating rate of 2oC/min and a period of 40 sec for C2 specimens crystallized nonisothermally at various cooling rates indicated in the figure. 78
Figure 12. Reversing heat flow of TMDSC data at a heating rate of 2oC/min and a period of 40 sec for C2 specimens crystallized nonisothermally at various cooling rates indicated in the figure. 78
Figure 13. Non-reversing heat flow of TMDSC data at a heating rate of 2oC /min and a period of 40 sec for C2 specimens crystallized nonisothermally at various cooling rates indicated in the figure. 79
Figure 14. WAXD powder pattern of C2 copolyester after the sample was crystallized isothermally for different time at the indicated temperature ranging from 180~204oC. 79
Figure 15. WAXD powder pattern of C2 copolyester after the sample was crystallized isothermally for different time at the indicated temperature ranging from 183~207oC. 80
Figure 16. HTWAXD powder pattern of C2 copolyester crystallized isothermally at 212oC for 24 h. 80
Figure 17. DSC thermograms at a heating rate of 80oC/min for C3 copolyester specimens isothermally crystallized at various temperatures indicated in the figure. 81
Figure 18. DSC thermograms at a heating rate of 80oC/min for C3 copolyester specimens isothermally crystallized at various temperatures indicated in the figure. 81
Figure 19. DSC nonisothermal crystallization curves of C3 copolyester at various cooling rates. (Sample was preheated from room temperature up to 215oC at 20oC/min and maintained at 215oC for 5 min). 82
Figure 20. Plots of relative crystallinity XT versus crystallization temperature for C3 copolyester crystallized nonisothermally at various cooling rates. 82
Figure 21. Plots of relative crystallinity XT versus crystallization time for C3 copolyester crystallized nonisothermally at various cooling rates. 83
Figure 22. Plots of log[-ln(1- XT)] versus logR at indicated temperature for C3 copolyester crystallized nonisothermally at various cooling rates. 83
Figure 23. Avrami plots of relative crystallinity XT for C3 copolyester crystallized nonisothermally at various cooling rates. 84
Figure 24. DSC thermograms at a heating rate of 50oC/min for the melt-crystallized C3 samples cooled from melting state at various cooling rates indicated in the figure. 84
Figure 25. Total heat flow of TMDSC data at a heating rate of 3oC/min and a period of 40 sec for C3 specimens crystallized nonisothermally at various cooling rates indicated in the figure. 85
Figure 26. Reversing heat flow of TMDSC data at a heating rate of 3oC/min and a period of 40 sec for C3 specimens crystallized nonisothermally at various cooling rates indicated in the figure. 85
Figure 27. Non-reversing heat flow ofTMDSC data at a heating rate of 3oC/min and a period of 40 sec for C3 specimens crystallized nonisothermally at various cooling rates indicated in the figure. 86
Figure 28. WAXD powder pattern of C3 copolyester after the sample was crystallized isothermally for different time at the indicated temperature ranging from 126~166oC. 86
Figure 29. WAXD powder pattern of C3 copolyester after the sample was crystallized isothermally for different time at the indicated temperature ranging from 130~170oC. 87
Figure 30. HTWAXD powder pattern of C3 copolyester crystallized isothermally at 174oC for 12 h. The asterisk (*) indicates the major reflection in the diffraction peak. 87
Figure 31. DSC thermograms at a heating rate of 80oC/min for C4 copolyester specimens isothermally crystallized at various temperatures indicated in the figure. 88
Figure 32. DSC thermograms at a heating rate of 80oC/min for C4 copolyester specimens isothermally crystallized at various temperatures indicated in the figure. 88

Figure 33. DSC nonisothermal crystallization curves of C4 copolyester at various cooling rates. (Sample was preheated from room temperature up to 192oC at 20oC/min and maintained at 192oC for 5 min). 89
Figure 34. Plots of relative crystallinity XT versus crystallization temperature for C4 copolyester crystallized nonisothermally at various cooling rates. 89
Figure 35. Plots of relative crystallinity XT versus crystallization time for C4 copolyester crystallized nonisothermally at various cooling rates. 90
Figure 36. Plots of log[-ln(1-XT)] versus logR at indicated temperature for C4 copolyester crystallized nonisothermally at various cooling rates. 90
Figure 37. Avrami plots of relative crystallinity XT for C4 copolyester crystallized nonisothermally at various cooling rates. 91
Figure 38. DSC thermograms at a heating rate of 50oC/min for the melt-crystallized C4 samples cooled from melting state at various cooling rates indicated in the figure. 91
Figure 39. Total heat flow of TMDSC data at a heating rate of 3oC/min and a period of 40 sec for C4 specimens crystallized nonisothermally at various cooling rates indicated in the figure. 92
Figure 40. Reversing heat flow of TMDSC data at a heating rate of 3oC/min and a period of 40 sec for C4 specimens crystallized nonisothermally at various cooling rates indicated in the figure. 92
Figure 41. Non-reversing heat flow of TMDSC data at a heating rate of 3oC/min and a period of 40 sec for C4 crystallized nonisothermally at various cooling rates indicated in the figure. 93
Figure 42. WAXD powder pattern of C4 copolyester after the sample was crystallized isothermally for different time at the indicated temperature ranging from 120~160oC. 93
Figure 43. WAXD powder pattern of C4 copolyester after the sample was crystallized isothermally for different time at the indicated temperature ranging from 124~156oC. 94
Figure 44. HTWAXD powder pattern of C4 copolyester crystallized isothermally at 164oC for 12 h. The asterisk (*) indicates the major reflection in the diffraction peak. 94
Figure 45. DSC thermograms at a heating rate of 80oC/min for C6 copolyester specimens isothermally crystallized at various temperatures indicated in the figure. 95
Figure 46. DSC nonisothermal crystallization curves of C6 copolyester at various cooling rates. (Sample was preheated from room temperature up to 228oC at 20oC/min and maintained at 228oC for 5 min). 95
Figure 47. Plots of relative crystallinity XT versus crystallization temperature for C6 copolyester crystallized nonisothermally at various cooling rates. 96
Figure 48. Plots of relative crystallinity XT versus crystallization time for C6 copolyester crystallized nonisothermally at various cooling rates. 96
Figure 49. Plots of log[-ln(1-XT)] versus logR at indicated temperature for C6 copolyester crystallized nonisothermally at various cooling rates. 97
Figure 50. Avrami plots of relative crystallinity XT for C6 copolyester crystallized nonisothermally at various cooling rates. 97
Figure 51. DSC thermograms at a heating rate of 50oC /min for the melt-crystallized C6 samples cooled from melting state at various cooling rates indicated in the figure. 98

Figure 52. Total heat flow of TMDSC data at a heating rate of 3oC/min and a period of 40 sec for C6 crystallized nonisothermally at various cooling rates indicated in the figure. 98
Figure 53. Reversing heat flow of TMDSC data at a heating rate of 3oC/min and a period of 40 sec for C6 specimens crystallized nonisothermally at various cooling rates indicated in the figure. 99
Figure 54. Non-reversing heat flow of TMDSC data at a heating rate of 3oC/min and a period of 40 sec for C6 s crystallized nonisothermally at various cooling rates indicated in the figure. 99
Figure 55. WAXD powder pattern of C6 copolyester after the sample was crystallized isothermally for different time at the indicated temperature ranging from 136~184oC. 100
Figure 56. WAXD powder pattern of C6 copolyester after the sample was crystallized isothermally for different time at the indicated temperature ranging from 140~188oC. 100
Figure 57. DSC nonisothermal crystallization curves of C7 copolyester at various cooling rates (sample was preheated from room temperature up to 234oC at 20oC/min and maintained at 234oC for 5 min). 101
Figure 58. Plots of relative crystallinity XT versus crystallization temperature for C7 copolyester crystallized nonisothermally at various cooling rates. 101
Figure 59. Plots of relative crystallinity XT versus crystallization time for C7 copolyesters crystallized nonisothermally at various cooling rates. 102
Figure 60. Plots of log[-ln(1-XT)] versus logR at indicated temperature for C7 copolyesters crystallized nonisothermally at various cooling rates. 102
Figure 61. Avrami plots of relative crystallinity XT for C7 copolyester crystallized nonisothermally at various cooling rates. 103
Figure 62. DSC thermograms at a heating rate of 50oC /min for the melt-crystallized C7 samples cooled from melting state at various cooling rates indicated in the figure. 103
Figure 63. Total heat flow of TMDSC data at a heating rate of 3oC/min and a period of 40 sec for C7 specimens crystallized nonisothermally at various cooling rates indicated in the figure. 104
Figure 64. Reversing heat flow of TMDSC data at a heating rate of 3oC/min and a period of 40 sec for C7 crystallized nonisothermally at various cooling rates indicated in the figure. 104
Figure 65. Non-reversing heat flow of TMDSC data at a heating rate of 3oC/min and a period of 40 sec for C7 specimens crystallized nonisothermally at various cooling rates indicated in the figure. 105
Figure 66. WAXD powder pattern of C7 copolyester after the sample was crystallized isothermally for different time at the indicated temperature ranging from 144~192oC. 105
Figure 67. WAXD powder pattern of C7 copolyester after the sample was crystallized isothermally for different time at the indicated temperature ranging from 148~188oC. 106
Figure 68. DSC thermograms at a heating rate of 80oC/min for C8 copolyester specimens isothermally crystallized at various temperatures indicated in the figure. 106
Figure 69. DSC thermograms at a heating rate of 80oC/min for C8 copolyester specimens isothermally crystallized at various temperatures indicated in the figure. 107
Figure 70. DSC nonisothermal crystallization curves of C8 copolyester at various cooling rates. (Sample was preheated from room temperature up to 276oC at 20oC/min and maintained at 276oC for 5 min). 107
Figure 71. Plots of relative crystallinity XT versus crystallization temperature for C8 copolyester crystallized nonisothermally at various cooling rates. 108
Figure 72. Plots of relative crystallinity XT versus crystallization time for C8 copolyester crystallized nonisothermally at various cooling rates. 108
Figure 73. Plots of log[-ln(1- XT)] versus logR at indicated temperature for C8 copolyester crystallized nonisothermally at various cooling rates. (Sample was preheated from room temperature up to 245oC at 20oC/min and maintained at 276oC for 5 min). 109
Figure 74. Plots of log[-ln(1- XT)] versus logR at indicated temperature for C8 copolyester crystallized nonisothermally at various cooling rates. (Sample was preheated from room temperature up to 270oC at 20oC/min and maintained at 270oC for 5 min). 109
Figure 75. Plots of log[-ln(1- XT)] versus logR at indicated temperature for C8 copolyester crystallized nonisothermally at various cooling rates. (Sample was preheated from room temperature up to 265oC at 20oC/min and maintained at 265oC for 5 min). 110
Figure 76. Avrami plots of relative crystallinity XT for C8 copolyester crystallized nonisothermally at various cooling rates. 110
Figure 77. DSC thermograms at a heating rate of 50oC/min for the melt-crystallized C8 samples cooled from melting state at various cooling rates indicated in the figure. 111
Figure 78. Total heat flow of TMDSC data at a heating rate of 3oC/min and a period of 40 sec for C8 specimens crystallized nonisothermally at various cooling rates indicated in the figure. 111
Figure 79. Reversing heat flow of TMDSC data at a heating rate of 3oC/min and a period of 40 sec for C8 specimens crystallized nonisothermally at various cooling rates indicated in the figure. 112
Figure 80. Non-reversing heat flow of TMDSC data at a heating rate of 3oC/min and a period of 40 sec for C8 crystallized nonisothermally at various cooling rates indicated in the figure. 112
Figure 81. WAXD powder pattern of C8 copolyester after the sample was crystallized isothermally for different time at the indicated temperature ranging from 176~216oC. 113
Figure 82. WAXD powder pattern of C8 copolyester after the sample was crystallized isothermally for different time at the indicated temperature ranging from 180~220oC. 113
Figure 83. DSC heating (A) and cooling (B) thermograms for melt-quenched copolyesters of (a) PTT；(b) PT91/ET9；(c) PT66/ET34；(d) PT62/ET38；(e) PT50/ET50；(f) PT28/ET72；(g) PT22/ET78；(h) PT9/ET91；(i) PET. 114
Figure 84. X-ray diffraction patterns of the melt-crystallized copolyesters of (a) PTT；(b) PT91/ET9；(c) PT66/ET34；(d) PT62/ET38；(e) PT50/ET50；(f) PT28/ET72；(g) PT22/ET78；(h) PT9/ET91；(i) PET. The asterisk (*) indicates the major reflection in the diffraction peak. 115
Figure 85. Changes of d spacings for the melt-crystallized copolyester as a function of the copolymer composition. 116
Figure 86. WAXD powder pattern of C5 copolyester after the sample was crystallized isothermally for different time at the indicated temperature ranging from 115~145oC. 116
Figure 87 IR spectra of C5 copolyester after the sample was crystallized isothermally for different time at the indicated temperature ranging from 115~145oC. 117
Figure 88. IR spectra of C5 PET/PTT copolyester; upper trace, crystalline sample; lower trace, amorphous sample. 117
Figure 89. Transmission pinhole photographs of uniaxially oriented copolymer of (a) PT91/ET9；(b) PT66/ET34；(c) PT62/ET38；(d) PT50/ET50. The fiber axis is vertical. 118
Figure 90. Transmission pinhole photographs of Uniaxially oriented copolymer of (e) PT28/ET72；(f) PT22/ET78；(g) PT9/ET91 copolymer. The fiber axis is vertical. 119

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