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

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Results and Discussion 134 The power of 1500 W has been selected for two reasons: 1. The electromagnetic energy transfer with the sample is optimized, as verified in the section 2.6 on page 85; 2. The microwave thermal profile is comparable with a DSC dynamic scan. The thermal profile of the sample, during this cure process has been monitored through the IR sensor of the microwave plant, because in dynamic operative conditions the datalogger is not usable, as explained in the section 2.5 on page 83. A comparable thermal profile between conventional DSC and microwave cure has been chosen in a sequence of microwave cure at different time from 90 to 300 s. The best agreement between both profiles has been achieved with a microwave cure of 240 s (16 passages) and a DSC dynamic scan at heating rate of 20 ◦ C/min from room temperature up to 250 ◦ C. Figure 3.29 shows in the same scale the comparison of these two thermal profiles. Figure 3.29: Comparison of the thermal profiles between MW cure process and DSC dynamic scan. During the MW exposure cycle the sample is not always submitted to the same energy density, because the tray sample-holder has an alternating movement 134
Results and Discussion 135 forward and backward from the multimodal cavity applicator. Only the maximum temperature of every passage is recorded. Presumably the average temperature, experienced by sample during MW cure, is lower than the recorded values. The MW thermal profile, which have been compared with a dynamic scan at 20 ◦ C/min in DSC, is influenced by this alternating monitoring of the sample temperature. Also in this case after every partial microwave cure process the degree of conversion of the sample has been estimated, through evaluation of residual enthalpy (∆H RES ), measured with a DSC dynamic scan between 0 and 220 ◦ C with heating rate of 10 ◦ C/min according to equation 3.27. α =1− ∆H RES ∆H TOT (3.27) For the sake of comparison with DSC curing process, the enthalpy value [16] of 462,2 J/g (∆H TOT ), measured during DSC dynamic scan at 20 ◦ C/min from room temperature up to 250 ◦ C, as illustrated in Figure 3.30, has been chosen, even though results obtained at different heating rates slight differ. Figure 3.30: Total cure energy with DSC dynamic scan at 20 ◦ C/min. As an example in Figure 3.31 the residual energy, after a microwave cure of 240 s, is shown. 135
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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
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Experimental 61 Figure 2.5: Right s
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Experimental 63 Figure 2.8: Front v
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Experimental 65 regardless of the a
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Experimental 67 • The number of t
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Experimental 69 Figure 2.11: Surfac
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Experimental 71 Figure 2.12: Repeti
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Experimental 73 From the Figure 2.1
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Experimental 75 in the centre of th
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Experimental 77 not read the water
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Experimental 79 Test number 1 2 3 4
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Experimental 81 Figure 2.19: Plot o
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Page 87 and 88: Experimental 87 Material Behaviour
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Page 109 and 110: Results and Discussion 109 Kinetic
Page 111 and 112: Results and Discussion 111 Figure 3
Page 113 and 114: Results and Discussion 113 3.3 Comp
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Page 117 and 118: Results and Discussion 117 Tables 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
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Page 147 and 148: Results and Discussion 147 3.23 and
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Page 153 and 154: Results and Discussion 153 Flexural
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Page 163 and 164: Conclusions and Outlook 163 degree
Page 165 and 166: Appendix A A Brief History of Micro
Page 167 and 168: A Brief History of Microwave Oven 1
Page 169 and 170: Bibliography [1] W. Callister, “M
Page 171 and 172: BIBLIOGRAPHY 171 [19] P. I. Karkana
Page 173: BIBLIOGRAPHY 173 [34] K. D. V. Pras
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