Title Page
Contents
ABSTRACT 16
Chapter 1. INTRODUCTION 18
1.1. Scope of this study 19
1.2. Background 23
1.2.1. Changing trends in energy systems 23
1.2.2. Strategies to enhance energy efficiency of solar cell 27
1.2.3. Framework in segmented PEMFC system 30
1.2.4. Thermal interface material (TIM) in battery assembly 33
References 36
Chapter 2. All-Cellulose Paper with High Optical Transmittance and Haze Fabricated via Electrophoretic Deposition 44
ABSTRACT 45
2.1. Introduction 46
2.2. Experimental 49
2.2.1. Materials and preparation of CNF/CMC dispersion 49
2.2.2. Preparation of cellulose paper by EPD 49
2.2.3. Characterization 50
2.3. Results and Discussion 52
2.3.1. Materials characterization and EPD set-up 52
2.3.2. Film fabrication and morphology characterization 55
2.3.3. CNF/CMC film thickness control 57
2.3.4. Optical characteristics of CNF/CMC films 59
2.3.5. Mechanical characteristics of CNF/CMC films 65
2.3.6. Water resistance of CNF/CMC films 67
2.4. Conclusions 70
Supporting information 72
References 76
Chapter 3. Low Dielectric Constant and Anisotropic Mechanical Properties of Dispenser-Printed Polyetherimide Films Using Two-Step Thermal Treatment 81
ABSTRACT 82
3.1. Introduction 83
3.2. Experimental 86
3.2.1. PEI ink preparation 86
3.2.2. Fabrication of dispenser-printed PEI films 86
3.2.3. Characterization 87
3.3. Results and discussion 89
3.3.1. Solvent selection and ink viscosity measurement 89
3.3.2. Appropriate ink selection and printing condition optimization 92
3.3.3. Investigation of heating condition 94
3.3.4. Printing PEI films and its thickness control 96
3.3.5. Dielectric and thermal characteristics of PEI films 98
3.3.6. Mechanical characteristics of PEI films 101
3.4. Conclusions 103
Supporting information 104
References 106
Chapter 4. Non-combustible and Thermally Conductive Polytetrafluoroethylene/magnesium hydroxide/expandable graphite Composites 113
ABSTRACT 114
4.1. Introduction 115
4.2. Experimental 119
4.2.1. Materials and composite fabrication methods 119
4.2.2. Characterization 120
4.3. Results and discussion 121
4.3.1. Fabrication process and mechanism of PEM composites 121
4.3.2. Morphologies of materials and composites 124
4.3.3. Thermal stability of materials and PEM composites 126
4.3.4. Flame retardancy of PEM composites 128
4.3.5. Combustion behavior of PEM composites 130
4.4. Conclusions 133
Supporting Information 135
References 140
Chapter 5. Conclusions 144
5.1. Cellulose-based film with high optical transmittance and haze fabricated via electrophoretic deposition 145
5.2. Dispenser-printed polyetherimide film and their characteristics based on printing direction and annealing conditions 146
5.3. Non-combustible and thermally conductive composite films achieved by extremely high loading of flame retardant additives 147
논문요약 149
Table 2.1. Comparison of various transparent and hazy cellulose films with our all-cellulose films. 62
Table 3.1. Dielectric and thermal properties depending on heating time. 100
Table 3.2. Mechanical properties following heating time and printing direction. 102
Table 4.1. Composition of PEM composites. 119
Table 4.2. LOI and UL-94 results of PEM composites. 129
Table 4.3. pHRR, THR, and thermal conductivity of PEM composites. 132
Table S2.1. Optical properties of CNF/CMC3 and CNF/CMC5 films depending on sonication time. 73
Table S2.2. ΦT and ΦH values of CNF/CMC3 and CNF/CMC5 films.[이미지참조] 74
Table S2.3. BoxLucas1 fitting results for the time-dependent water absorption of CNF/CMC3 and CNF/CMC5 films. 75
Table S3.1. Density of theoretical and printed PEI under different pressure. 104
Table S4.1. Maximum weight loss rate of MH and PEM composites 136
Table S4.2. Comparison of the flame-retardant performance of various metal hydroxide incorporated composites. 138
Figure 1.1. Schematic illustration of categorized research topics; cellulose film, PEI film, and composite film. 22
Figure 1.2. Total U.S. greenhouse gas emissions by economic sectors and promising solutions. 26
Figure 1.3. Schematic illustration of scattering mechanism by (a) Rayleigh scattering [36] and (b) rough surface layer. 29
Figure 1.4. (a) Mechanism and (b) structure of segmented fuel cell system. 32
Figure 2.1. (a) Zeta potential of CNF dispersion as a function of pH: The inset exhibits the digital image of the anode surface covered with CMC after EPD at... 54
Figure 2.2. (a) Photographs of the dried brass electrode after the EPD process with CNF, (b) CMC, and (c) CNF/CMC mixture. SEM images of (d) CNF, (e)... 56
Figure 2.3. (a) Photographs of the deposited CNF/CMC3 suspension with different deposition time at 3 V. (b) Thickness of CNF/CMC3 films plotted as a... 58
Figure 2.4. (a) The dependency of transmittance and (b) haze of CNF/CMC film on ultrasonic time and ratio of CNF and CMC. (c) Comparison of the optical... 61
Figure 2.5. (a) Photographs of CNF/CMC5_1h film and (b) PET film placed on the printed letters; placed right on the letters and 3 cm separated from the... 64
Figure 2.6. (a) Characterizations of the mechanical properties for CNF/CMC papers with only CMC, CNF/CMC5_1h and CNF/CMC3_1h films, respectively.... 66
Figure 2.7. (a) Digital images of CMC, CNF/CMC3, and CNF/CMC5 films after immersing into water for 10 min. (b) Water contact angles of the CMC,... 69
Figure 3.1. Schematic illustration of the overall process for PEI film fabrication. Inset digital images show the PEI chemical structure, NMP/PEI solution with... 90
Figure 3.2. Viscosities of NMP/PEI10, NMP/PEI20, and NMP/PEI30 inks as a function of shear rate. 91
Figure 3.3. Digital images of (a) NMP/PEI10, (b) NMP/PEI20, and (c) NMP/PEI30 inks while printed under the pneumatic pressures of 0, 50, and 200... 93
Figure 3.4. (a) TGA curves of NMP/PEI10, NMP/PEI20, and NMP/PEI30 inks. (b) FT-IR spectra of PEI films after one-step heat treatment (100 °C for 2... 95
Figure 3.5. Digital images of (a) annealed PEI printed in a complicated pattern, (b) PEI films in different shapes fabricated by two-step heat treatment, and (c)... 97
Figure 3.6. (a) Dielectric constant as a function of frequency and (b) dimensional change of two-step heat-treated PEI films with different annealing... 100
Figure 3.7. As-prepared PEI films along with (a) longitudinal and (b) transversal directions. (c) Tensile strength and (d) modulus of the PEI films at... 102
Figure 4.1. The schematic illustrations of (a) fabrication process of PEM composites and (b) their multifunctionality of heat dissipation and fire suppression. 123
Figure 4.2. FE-SEM images of (a) MH, (b) EG, PTFE (c) before and after (d,e) fibrillation, and (f) the PEM10 composites with different magnification. The... 125
Figure 4.3. (a) TGA and (b) DTG curves of PEM composites in the temperature range of 50-600 ℃. 127
Figure 4.4. Digital images of UL-94 vertical combustion test of PEM5. 129
Figure 4.5. (a) Digital photos of PEM composites during cone calorimetry and the comparison of THR and pHRR of metal hydroxide incorporated flame-... 131
Figure S2.1. (a) Digital images of CNF, CMC, CNF/CMC3, CNF/CMC5 dispersions at pH 8.0 taken right after prepared and (b) taken after 24 h,... 72
Figure S2.2. (a) Enlarged image of CNF deposited electrode showing many cracks. (b) Self-standing CMC film. (c) Flexible CNF/CMC3 film. 72
Figure S2.3. (a) Light transmittance of the CMC film and CNF/CMC3 films, and (b) CNF/CMC5 films in the wavelength range of 400-800 nm. 73
Figure S2.4. (a) Optical microscope images of CMC, (b) CNF/CMC3_1h, and (c)CNF/CMC5_1h films, respectively. 74
Figure S2.5. Water absorption and thickness change of CNF/CMC3 film as a function of immersion time. 75
Figure S4.1. (a) MH, EG, and PTFE mixed powder after mixing and (b) dough-like structure of materials after manual pressing. 135
Figure S4.2. (a) agglomerated sphere-shaped and (b) flexible film shaped PEM10 composites. 135
Figure S4.3. (a) TGA and (b) DTG of PTFE, MH, and EG in the range of 50-600 ℃ measured under nitrogen atmosphere. 136
Figure S4.4. Heat release rate of (a) PEM5, (b) PEM10, (c) PEM15, and (d) PEM 20 measured during cone calorimeter test. 137