A reactive melt modification of polyethylene terephthalate

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2 Figure 1.1 Macromolecular formula of polyethylene terephthalate (PET). Various combinations of reactant(s) and process conditions are potentially available to synthesize polyesters (Goodman, 1988). Commercial scale production of PET most commonly involves two steps. PET is generally prepared by bulk or solution polymerization initially at around 150-210°C by transesterification (alcoholysis) from dimethyl terephthalate (DMT) and ethylene glycol (EG) or direct esterification from terephthalic acid (TPA) and EG, in the presence of catalysts, resulting in oligomers. In a second step, oligomers undergo melt polycondensation to produce high molecular weight PET resin. In the case of reaction between DMT and EG, the methyl end groups of DMT are continuously replaced by ethyl end-groups of EG to produce bis (2-hydroxyethyl) terephthalate as shown in reaction (1) in Figure 1.2, along with small amounts of oligomers (Odian, 1991). In this process, EG is consumed while methanol is evaporated and re-collected to be returned to the DMT plant. The reactants are heated at temperatures increasingly from 150 to 210 °C. Commonly used catalysts for ester transformation are oxides, carbonates, or acetates of calcium; manganese; cobalt; cadmium; lead or zinc (Sorenson et al., 2001). Typically, the amount of catalyst used is in the range of 0.05 to 0.1% by weight of the dimethyl terephthalate (Cimecioglu, 1986). In the second-stage, the temperature is raised to 270-280 °C and polymerization proceeds with the removal of ethylene glycol being facilitated by using a partial vacuum
3 of 0.5-1.00 mm Hg (Sorenson 2001). Antimony oxide (Sb203) is generally used as a second-stage catalyst. Sometimes germanium oxide (Ge02) is added as a catalyst to the second stage also (Maréchal, 2001). Sb203 alone is known to be ineffective for the first stage reaction. The first stage catalyst is often deactivated by the addition of an alkyl or aryl phosphite or phosphate to reduce thermal degradation during the second stage. (Odian, 1991, Fakirov, 2002). Figure 1.2 PET synthesis from dimethyl terephthalate and ethylene glycol. The availability of terephthalic acid in higher purity than previously available has led to its use in a modification of a two-stage process (Odian, 1991). Terephthalic acid and an excess ethylene glycol (in the form of a paste) are used to produce the bis (2- hydroxyethyl) terephthalate as shown in Figure 1.3. The reaction is carried out at a temperature of about 200 °C at atmospheric pressure to eliminate water and form diolended polyester. This step is self-catalyzed by terephthalic acid. The second step consists
Page 1 and 2: Copyright Warning & Restrictions Th
Page 3 and 4: ABSTRACT REACTIVE MELT MODIFICATION
Page 5 and 6: REACTIVE MELT MODIFICATION OF POLYE
Page 7 and 8: BIOGRAPHICAL SKETCH Author: Rahul R
Page 9 and 10: Copyright © 2003 by Rahul Ramesh D
Page 11 and 12: ACKNOWLEDGEMENTS I always considere
Page 13 and 14: TABLE OF CONTENTS Chapter Page 1 IN
Page 15 and 16: TABLE OF CONTENTS (Continued) Chapt
Page 17 and 18: LIST OF FIGURES Figure Page 1.1 Mac
Page 19 and 20: LIST OF FIGURES (Continued) Figure
Page 21 and 22: LIST OF FIGURES (Continued) Figure
Page 23 and 24: Striation Thickness Time Diffusion
Page 25 and 26: tertiary amine terephthalic acid th
Page 27: CHAPTER 1 INTRODUCTION After its in
Page 31 and 32: where rib is the solution viscosity
Page 33 and 34: 7 are not suitable for most of the
Page 35 and 36: 9 In the case of sheet applications
Page 37 and 38: 11 operation (Dealy and Wissbrun, 1
Page 39 and 40: 13 During the cell growth phase of
Page 41 and 42: 15 suitability of extruders as cont
Page 43 and 44: 17 conditions and additive concentr
Page 45 and 46: 19 understand the effect of evolvin
Page 47 and 48: CHAPTER 3 LITERATURE REVIEW This ch
Page 49 and 50: 23 absence of modifiers is accompan
Page 51 and 52: 25 The primary objective while modi
Page 53 and 54: 27 Polypropylene resins with high m
Page 55 and 56: 29 initially the reaction with hydr
Page 57 and 58: 31 A diglycidyl ether, often in the
Page 59 and 60: 33 Characterizing the products of t
Page 61 and 62: 35 5. Ease of mixing in the polymer
Page 63 and 64: 37 Figure 3.4 Epoxy or 0xirane ring
Page 65 and 66: 39 carbocation stability overrides
Page 67 and 68: 41 Figure 3.9 Anhydride — epoxy r
Page 69 and 70: 43 Figure 3.12 Base catalyzed hydro
Page 71 and 72: 45 activity to enhance the PET-epox
Page 73 and 74: 47 4.1.2 Chain EDtenders The struct
Page 75 and 76: TGDDM was used in the batch mixer s
Page 77 and 78: 51 4.2 Processing and Characterizat
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53 specimens as a function of freVu
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55 to the parallel plates). An addi
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57 background spectrum. It took app
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CHAPTER 5 RESULTS AND DISCUSSION Th
Page 87 and 88:
61 molecular weight of MPET as also
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63 rate expressions analogous to th
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Figure 5.5 Possible reactions betwe
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67 taking place by the convective;
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69 5.1.4 Comparison of Epoxides Fig
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71 5.1.5 Reactions of TGIC with HPE
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73 Figure 5.11 shows the vanation o
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75 Figure 5.13 shows the effect of
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77 to time. In a general sense, the
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79 5.1.7 Study on Role of Catalysts
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81 groups adjacent to the tertiary
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83 overall less activity towards TG
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85 5.2.1 Typical Batch MiDing Runs
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87 It appears that the higher proce
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89 injection (Dealy and Wissbrun, 1
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91 rheological power scaling law fo
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93 In the calculations, the freVuen
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95 whereas H(?.) of the unmodified
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97 However, the disintegration of t
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99 the Section 4.1.3. As evident fr
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101 changes in dynamic moduli and m
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103 In the case of 270 °C, the mod
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105 accessibility of unreacted grou
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107 believed to be charactenzed by
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109 increase in the melt elasticity
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111 In general, for crosslinked sys
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113 crosslinked gels in swelling eV
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115 formation of epoxy/PET reaction
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117 A seVuential reactive extrusion
Page 145 and 146:
CHAPTER 6 CONCLUSIONS AND RECOMMEND
Page 147 and 148:
121 of PET by the selected tnepoxid
Page 149 and 150:
REFERENCES S. Abe and M. Yamaguchi,
Page 151 and 152:
125 L. M. Dossin and W. W. Graessle
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127 P. Huang, Z. Zhong, S. Zheng, W
Page 155 and 156:
129 J. Meissner and J. Hostettler,
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131 T. Shiwaku, K. Hijikata, K. Fur
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133 M. Xanthos and S. K. Dey, "Foam
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A reactive melt modification of polyethylene terephthalate

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