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

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Results and Discussion 126 P 1500 W α i 0,5 T k(T) α ′ 0,5 367,15 K 0,99 min −1 0,11 min −1 α 0,5+τ 0,52 Table 3.14: Numerical values used for the evaluation of α 0,5+τ for MW cure at 1500 W. t MW [s] 40 50 55 60 75 100 T MW [ ◦ C] 73 84 87 93 – – α MW [%] 3,28 20,51 20,95 92,57 98,34 ≈ 100 Table 3.15: Time, temperature max and degree of conversion for MW cure at 2000 W. Figure 3.22: Degree of conversion against reaction time for MW cure process at 2000 W. 126
Results and Discussion 127 Figure 3.17 shows that the agreement between thermal profiles of MW cure process at a power of 2000 W and DSC at a heating rate of 70 ◦ C/min is almost perfect up to 60 s, corresponding to a degree of conversion of 92,57 %. Therefore, also in this case, the main part of the polymerization process occurs, following a thermal profile almost perfectly comparable with a DSC dynamic scan. The degree of conversion in conventional DSC at the heating rate of 44 ◦ C/min and 70 ◦ C/min has been measured integrating the signal at different temperatures, corresponding to the maximum temperature achieved in DSC scan after the same time of MW cure respectively at 1500 and 2000 W, increased with the delay time τ. Considering the comparison between the MW cure process at 1500 W and the polymerization in DSC at the heating rate of 44 ◦ C/min the degree of conversion in DSC has been calculated using the equation 3.26: α = ∆H PAR ∆H TOT (3.26) where ∆H TOT is the total cure energy, generated during a DSC dynamic scan between 0 and 250 ◦ C with heating rate of 44 ◦ C/min and measured as illustrated in Figure 3.23. Therefore the value of 448,7 J/g has been used. In Figure 3.24 an example of measurement of partial energy at a temperature of 124 ◦ C with a DSC dynamic scan at 44 ◦ C/min is illustrated. The Table 3.16 reports degree of conversion in DSC, obtained in this way. where T τ is the increase of temperature, during the DSC dynamic scan at heating rate of 44 ◦ C/min, due to the delay time τ and equal to 7, 33 ◦ C. As shown in the Table 3.16 after 175 s in DSC the system has reached only the 86,41% of degree of cure, while the same time in MW is sufficient to achieve the complete conversion. The profile of degree of cure in DSC against reaction time is illustrated in Figure 3.25. 127
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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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Page 117 and 118: Results and Discussion 117 Tables 3
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Page 129 and 130: Results and Discussion 129 t DSC [s
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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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