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

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Experimental 56 Then the components have been mechanically and carefully mixed and stirred, with a steel spatula, until clear mixture has been obtained. During this phase, generally air bubbles are formed inside the mixture. For this reason the system has been submitted to a degassing treatment, under vacuum at room temperature for 20 min. In this way the bubbles rise to the surface of the mixture and then it is possible to remove them with a technical spoon, or directly during the microwave radiation. During the mixture preparation the conversion is completely negligible. 2.2 Microwave Plant The samples, microwave cured, have been polymerized using a microwave multimodal cavity produced by Microglass s.r.l. placed in the Department of Materials and Production Engineering (DIMP) of University of Naples “Federico II”. This is a laboratory scale microwave oven, equipped with three heating mechanisms: 1. Hot air; 2. Infrared radiations; 3. Microwaves radiations. These can be used singularly or in combined way. The exposure time, under infrared and microwave radiations, can be chosen by the user, selecting the sampleholder tray velocity and the total number of passages to perform or the time with immovable tray. Moreover the plant can be used with moving or immovable tray. In this second case the sample is fixed under the waveguide for a preset time in order to use the oven as a static cavity. 56
Experimental 57 If the oven is used in static operative conditions the automatic cycle can be subdived in three steps: 1. Entrance: in this phase the tray enters inside the radiations cavity with the velocity, selected by the user, passing under the infrared region. If the IR heating is active, during this phase the infrared lamp is turned on; 2. Permanence under waveguide: after entrance of sample-holder tray, the safety door is closed and the microwave generator is turned on. During this phase, the hot air heating is also active and is based on the temperature set by the user; 3. Exit: when the second phase is ended, the microwave radiations is turned off, and the tray goes out, with the velocity set by the user, crossing the IR region. The automatic cycle is finished. If the oven is used in dynamic operative conditions the second phase foresees the alternating forward and backward movement of the tray under the waveguide for the number of passages and the velocity selected by the user. 2.2.1 Microwave Radiation System Mechanism The principle of operation of a microwave oven can be schematically presented through three blocks: radiations generator, waveguide and applicator as illustrated in Figure 2.1. The radiations generator is a magnetron, an electronic tube, suitable for generate high powers in microwave field. The magnetron of the microwave oven used in this work can supply powers from 0,5 to 2 KW. It is provided of an electronic kit, that delivers energy only if inside the oven the appropriate safety conditions are satisfied. In case of out of order conditions the control panel provides to interrupt the microwave radiations, displaying an error message on the control panel and opening the safety door. 57
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UNIVERSITA’ DEGLI STUDI DI NAPOLI
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3 I thank all the lecturers of PhD
Page 5 and 6: 5 Microwaves are electromagnetic ra
Page 7 and 8: CONTENTS 7 1.8.1 DielectricProperti
Page 9 and 10: CONTENTS 9 4 Conclusions and Outloo
Page 11 and 12: LIST OF TABLES 11 3.2 Average value
Page 13 and 14: List of Figures 1.1 Diglycidylether
Page 15 and 16: LIST OF FIGURES 15 2.23 Onset tempe
Page 17 and 18: LIST OF FIGURES 17 3.38 Comparison
Page 19 and 20: Introduction 19 cannot be melted an
Page 21 and 22: Introduction 21 • bismaleimides;
Page 23 and 24: Introduction 23 cold solders, casti
Page 25 and 26: Introduction 25 Average Properties
Page 27 and 28: Introduction 27 In Figure 1.4 n can
Page 29 and 30: Introduction 29 ducts and it genera
Page 31 and 32: Introduction 31 tween current-carry
Page 33 and 34: Introduction 33 that describe the p
Page 35 and 36: Introduction 35 1.3.5 Lorentz Force
Page 37 and 38: Introduction 37 Figure 1.11: Electr
Page 39 and 40: Introduction 39 Even microwaves can
Page 41 and 42: Introduction 41 production requirem
Page 43 and 44: Introduction 43 fect of the electro
Page 45 and 46: Introduction 45 following different
Page 47 and 48: Introduction 47 Debye equations bas
Page 49 and 50: Introduction 49 Although these mode
Page 51 and 52: Introduction 51 materials that have
Page 53 and 54: Chapter 2 Experimental In this chap
Page 55: Experimental 55 Characteristic Note
Page 59 and 60: 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
Page 75 and 76: Experimental 75 in the centre of th
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
Page 89 and 90: Experimental 89 in function of the
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
Page 101 and 102: Results and Discussion 101 After pr
Page 103 and 104: Results and Discussion 103 of insta
Page 105 and 106: Results and Discussion 105 1. Mecha
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Results and Discussion 107 where k
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Results and Discussion 109 Kinetic
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Results and Discussion 111 Figure 3
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Results and Discussion 113 3.3 Comp
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Results and Discussion 115 pedestal
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Results and Discussion 117 Tables 3
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Results and Discussion 123 t MW [s]
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Results and Discussion 125 simulate
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Results and Discussion 129 t DSC [s
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Results and Discussion 133 Using th
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Results and Discussion 135 forward
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Results and Discussion 141 than the
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Results and Discussion 143 Since ev
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Results and Discussion 145 ditions.
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Results and Discussion 147 3.23 and
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Results and Discussion 149 The T g
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Results and Discussion 151 3.6.1 St
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Results and Discussion 153 Flexural
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Results and Discussion 155 3.7.2 FT
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Results and Discussion 157 identifi
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Results and Discussion 159 This eff
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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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