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

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Results and Discussion 100 2. The heating of the sample at elevated temperature has promoted evaporation of the reagents and therefore the onset of plasticization phenomena. The glass transition temperature is equal to: T g = 103, 29 ◦ C (3.4) Unfortunately the microwave radiation time can not be accurately controlled, because it must be a multiple of the time of a single sample-holder tray passage. 3.2 DSC Kinetic Analysis The kinetic study of epoxy system has been performed using the DSC isothermal technique [16]. The first step consists of performance of isothermal DSC in a temperature range, selected on the basis of the DSC dynamic scan analysis. These temperatures should belong to the steepest portion of the dynamic thermogram, because in this case the reaction rate is the greatest. Moreover also temperatures higher than T g should be selected for considering also curing processes, in which vitrification phenomena have been avoided. Finally also the T g of the completely crosslinked resin has been used. 3.2.1 DSC Isothermal Scan The temperatures chosen for this kinetic analysis are reported in Table 3.4 Isothermal Temperatures Isothermal DSC temperatures [ ◦ C] 90 95 100 105 110 115 120 Table 3.4: Temperatures of isothermal DSC. 100
Results and Discussion 101 After preparation of fresh mixture, through the procedure illustrated in the section 2.1.3 on page 54, samples weighting 6 to 12 mg have been placed in an aluminum hermetic sample pans 3 in nitrogen atmosphere. The cell of DSC instrument has been heated until the achievement of the desired temperature. After instrument stabilization the sample pan has been quickly inserted inside the cell and the test has been started. As a matter of fact this experimental procedure is affected by an initial instrumental set-up, resulting in loss of data accuracy during the first 30-45 s. The test have been carried out for 40 min for ensuring a complete conversion, confirmed by the reaching of the horizontal asymptote of the specific heat flow versus time signal. The operative conditions, used during these test, have been summarized in Table 3.5. Operative Conditions Atmosphere Sample weight Sample pan Initial set-up Time Nitrogen 6-12 mg Aluminum hermetic 30-45 s 40 min Table 3.5: Operative conditions of isothermal DSC. These test generate data in the form of time, temperature and heat flow and therefore specific heat flow from the sample weight. Therefore the curve of specific heat flow [W/g] versus time [min] can be drawn. 3 The lid of the pan has been perforated for avoiding its deformation, due to the possible emission of volatiles during the DSC. 101
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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
Page 49 and 50: Introduction 49 Although these mode
Page 51 and 52: Introduction 51 materials that have
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Page 55 and 56: Experimental 55 Characteristic Note
Page 57 and 58: Experimental 57 If the oven is used
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Page 65 and 66: Experimental 65 regardless of the a
Page 67 and 68: Experimental 67 • The number of t
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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
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Page 91 and 92: Experimental 91 2.6.3 Influence of
Page 93 and 94: Chapter 3 Results and Discussion Th
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Page 97 and 98: Results and Discussion 97 Figure 3.
Page 99: 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
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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
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Page 149 and 150: 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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