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

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Experimental 70 is also important to position the sample along the reading cone of this sensor, especially when the oven is used with moving tray and there are not other reliable temperature monitoring systems 6 . In fact recording the temperature profile, during the curing process, is useful for the kinetic study and for a comparison between microwave and DSC crosslinking reaction 7 . 2.3.2 Energy Density Distribution The MW oven is provided of a system of vertical electromagnetic energy distribution inside the cavity, as illustrated in Figure 2.8. A mapping of applicator has been carried out for detecting the effective distribution of energy inside the cavity. Therefore some experiments have been performed for determining the dependence of energy density distribution along x-y and z axes. These experiments are based on the reasonable hypothesis that the energy density in any given position is proportional to the temperature raising of a fixed amount of a sample microwave sensitive, like tap water, when heated inside the oven, operating in the same conditions, and placed in this position. For the first case a cylindrical beaker of polypropylene of a total volume of 250 ml has been used. Vessels of PP have been selected, because they are transparent to microwaves, have a good thermal resistance 8 , are enough cheap and not very fragile. The repetitive unit of PP is illustrated in Figure 2.12. Polypropylene is a growth-step propylene polymer. It has an isotattic structure 9 , with elevated crystallinity. The isotattic omopolymer is very crystalline, and therefore it has a little transparency. While adding the 1,7% of ethylene a long copolymer, with random groups distribution, is obtained. This copolymer is very used as vessel 6 See the section 2.5 on page 83. 7 See the section 3.3 on page 113. 8 T f = 180 ◦ C. 9 Every group is on the same side of the backbone. 70
Experimental 71 Figure 2.12: Repetitive unit of polypropylene. in domestic microwave ovens for food heating. In fact the crystallinity variation makes the material very transparent. The beaker has been filled with tap water for a total volume of 250 ml. The initial water temperature has been measured with a digital thermocouple. Therefore the beaker has been placed, first in the centre of the vessel, and then in position always more peripheral. The Figure 2.13 shows a schematic representation of the beaker distribution on the tray surface. Figure 2.13: Beaker distribution on the tray surface. Beaker has been cooled and the water substituted, after each cycle. A cycle with the parameters reported in Table 2.3 has been set. The water temperature has 71
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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
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 and 56: Experimental 55 Characteristic Note
Page 57 and 58: Experimental 57 If the oven is used
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: Experimental 69 Figure 2.11: Surfac
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
Page 107 and 108: Results and Discussion 107 where k
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
Page 115 and 116: Results and Discussion 115 pedestal
Page 117 and 118: Results and Discussion 117 Tables 3
Page 119 and 120: Results and Discussion 119 Figure 3
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Results and Discussion 121 Figure 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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