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

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Experimental 88 Polytethrafluoroethylene Mould Geometry Shape Length Width Thickness Parallelepiped 150 mm 150 mm 4 mm Table 2.9: Shape and size of the polytethrafluoroethylene mould used for dynamical-mechanical characterization. 2.6.2 Influence of the Air Temperature The air temperature inside the microwave oven cavity exerts a meaningful effect on the cure process of the epoxy system. This parameter can be selected at the beginning of the automatic cycle in a range from 20 up to 80 ◦ C, but for safety reason it is not advisable to overcome for a long time the temperature of 60 ◦ C. Some qualitative experiments have been carried out with sample of thickness of 1 cm, submitted to the same power and radiation time, and changing only the air temperature. In Table 2.10 the parameters of the performed tests are reported. Test T air [ ◦ C] Power [W] Tray Velocity [ ] cm IR Time [s] min 1 60 2000 224 OFF 600 2 50 2000 224 OFF 600 3 40 2000 224 OFF 600 4 30 2000 224 OFF 600 Table 2.10: Parameters selected for investigating the influence of the air temperature. In every test the sample has been completely cured, assuming different colours 88
Experimental 89 in function of the air temperature, as illustrated in Figure 2.22. Figure 2.22: Samples cured with 2000 W for 10 min and with air temperature of 60 ◦ C (A), 50 ◦ C(B),40 ◦ C(C),30 ◦ C(D). The crosslinking reaction begins more quickly at higher temperatures, with a consequent thermal degradation of the cured system. Decreasing the air temperature the colour of polymerized sample is lighter, as illustrated in Figure 2.22. The centre of each sample is of dark red, because this is the region that dissipates, in the worse way, the heat generated during the reaction. A sample of 1 cm of thickness, with air temperature of 60 ◦ C, and without MW radiation, submitted to a cycle of 16 passages (4 min) appears very hard at the end of the cycle. As reported on the technical datasheet of Elantas Camattini S.p.A. 60 ◦ C is also the temperature, at which a conventional cure of 15 h can be performed. Moreover analyzing the curve of the specific heat flow versus temperature, obtained with a differential scanning calorimeter (DSC) test heating rate of 10 ◦ C/min, illustrated in Figure 2.23, about 60 ◦ C is also the onset temperature 26 . Finally a temperature of 25 ◦ C has been selected for performing the experiments in order to avoid the hazard of thermal degradation of the sample. 26 The temperature at which the steepest portion of the curve begins. 89
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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
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
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Page 79 and 80: Experimental 79 Test number 1 2 3 4
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Page 83 and 84: Experimental 83 2.5 Datalogger This
Page 85 and 86: Experimental 85 same reason a wood
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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 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 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 135 and 136: Results and Discussion 135 forward
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Results and Discussion 139 Figure 3
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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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Kinetic Analysis and Characterization of Epoxy Resins ... - FedOA

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