Kinetic Analysis and Characterization of Epoxy Resins ... - FedOA

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Results and Discussion 112 Figure 3.12: Arrhenius plot. From the equation of the interpolating line it is possible to calculate the values of activation energy E a and the hyperbolic logarithm of the pre-exponential factor ln (k 0 ) for the conventional curing process. E a =11, 41 · 1000 K · R=11, 41 · 1000 K · 8, 314472 J KJ =94, 84 mol K mol (3.19) ln (k 0 )=31, 06 1 (3.20) min The kinetic parameters are reported in Table 3.8. These values are in good Conventional Kinetic Parameters E a [KJ/mol] 94,84 ln (k 0 )[min −1 ] 31,06 Table 3.8: Kinetic parameters for conventional curing reaction. agreement with those obtained by Navabpour et al. [20]. 112
Results and Discussion 113 3.3 Comparison MW versus DSC A comparison of degree of conversion in function of reaction time during microwave and conventional DSC cure processes of the epoxy system, undergone almost the same thermal profile, has been performed for investigating the existence of the specific microwave effect. 3.3.1 Specific Microwave Effect Activating effects induced by electromagnetic wave absorption, and that cannot be easily emulated through conventional heating methods, remain a very controversial topic since the beginning of the use of microwave for supplying energy for chemical reactions [21, 22]. Therefore specific microwave effect is a non thermal effect of MW field, involving an acceleration of reaction rate 7 , and a variation of chemical reaction mechanism. Two fundamental explanations have been proposed for justifying this effect: 1. Effects depending on lifetime of transition state of reactants. In the case of short lifetime, the position hypothesis holds: the electric field would induce suitable positions of reactants that would minimize the entropy of the system. In the case of a very long lifetime, the electric field would induce an increasing probability of molecular collisions. Loupy et al. [23] have addressed the orienting effect of electric field, so microwave irradiation could induce molecular organization different from those induced by classical heating mode; 2. The occurrence of a difference between local temperature of electrical entities, i.e. dipolar moment associated with chemical bonds. 7 Not simply attributable to differences of heating rate or thermal profile. 113
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UNIVERSITA’ DEGLI STUDI DI NAPOLI
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3 I thank all the lecturers of PhD
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5 Microwaves are electromagnetic ra
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CONTENTS 7 1.8.1 DielectricProperti
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CONTENTS 9 4 Conclusions and Outloo
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LIST OF TABLES 11 3.2 Average value
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List of Figures 1.1 Diglycidylether
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LIST OF FIGURES 15 2.23 Onset tempe
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LIST OF FIGURES 17 3.38 Comparison
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Introduction 19 cannot be melted an
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Introduction 21 • bismaleimides;
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Introduction 23 cold solders, casti
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Introduction 25 Average Properties
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Introduction 27 In Figure 1.4 n can
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Introduction 29 ducts and it genera
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Introduction 31 tween current-carry
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Introduction 33 that describe the p
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Introduction 35 1.3.5 Lorentz Force
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Introduction 37 Figure 1.11: Electr
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Introduction 39 Even microwaves can
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Introduction 41 production requirem
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Introduction 43 fect of the electro
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Introduction 45 following different
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Introduction 47 Debye equations bas
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Introduction 49 Although these mode
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Introduction 51 materials that have
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Chapter 2 Experimental In this chap
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Experimental 55 Characteristic Note
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Experimental 57 If the oven is used
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Experimental 59 In monomodal applic
Page 61 and 62: Experimental 61 Figure 2.5: Right s
Page 63 and 64: Experimental 63 Figure 2.8: Front v
Page 65 and 66: Experimental 65 regardless of the a
Page 67 and 68: Experimental 67 • The number of t
Page 69 and 70: Experimental 69 Figure 2.11: Surfac
Page 71 and 72: Experimental 71 Figure 2.12: Repeti
Page 73 and 74: Experimental 73 From the Figure 2.1
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Page 77 and 78: Experimental 77 not read the water
Page 79 and 80: Experimental 79 Test number 1 2 3 4
Page 81 and 82: Experimental 81 Figure 2.19: Plot o
Page 83 and 84: Experimental 83 2.5 Datalogger This
Page 85 and 86: Experimental 85 same reason a wood
Page 87 and 88: Experimental 87 Material Behaviour
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Page 91 and 92: Experimental 91 2.6.3 Influence of
Page 93 and 94: Chapter 3 Results and Discussion Th
Page 95 and 96: Results and Discussion 95 There is
Page 97 and 98: Results and Discussion 97 Figure 3.
Page 99 and 100: Results and Discussion 99 Parameter
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Page 105 and 106: Results and Discussion 105 1. Mecha
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Page 109 and 110: Results and Discussion 109 Kinetic
Page 111: Results and Discussion 111 Figure 3
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Page 117 and 118: Results and Discussion 117 Tables 3
Page 119 and 120: Results and Discussion 119 Figure 3
Page 123 and 124: Results and Discussion 123 t MW [s]
Page 125 and 126: Results and Discussion 125 simulate
Page 129 and 130: Results and Discussion 129 t DSC [s
Page 133 and 134: Results and Discussion 133 Using th
Page 135 and 136: Results and Discussion 135 forward
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Page 143 and 144: Results and Discussion 143 Since ev
Page 145 and 146: Results and Discussion 145 ditions.
Page 147 and 148: Results and Discussion 147 3.23 and
Page 149 and 150: Results and Discussion 149 The T g
Page 151 and 152: Results and Discussion 151 3.6.1 St
Page 153 and 154: Results and Discussion 153 Flexural
Page 155 and 156: Results and Discussion 155 3.7.2 FT
Page 157 and 158: Results and Discussion 157 identifi
Page 159 and 160: Results and Discussion 159 This eff
Page 161 and 162: Results and Discussion 161 Also in
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Conclusions and Outlook 163 degree
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Appendix A A Brief History of Micro
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A Brief History of Microwave Oven 1
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Bibliography [1] W. Callister, “M
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BIBLIOGRAPHY 171 [19] P. I. Karkana
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BIBLIOGRAPHY 173 [34] K. D. V. Pras
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