Title Page
국문요약
ABSTRACT
Contents
Chapter 1. Background and Objectives 20
1.1. General Background 20
1.2. Epoxy resin systems 21
1.2.1. Types of epoxy resins 22
1.2.2. Types of curing agents 23
1.3. Interface of epoxy-based composites 24
1.4. Interfacial interactions in epoxy-based composites 25
1.4.1. Covalent and noncovalent interactions 26
1.4.2. Experimental methods of measuring interfacial properties 27
1.5. Addition of fillers to the epoxy matrix 29
1.5.1. Thermal stability 30
1.5.2. Thermal conductivity 32
1.5.3. Strength 36
1.5.4. Toughness 37
1.6. The Objectives of the Works 39
Chapter 2. Experimental Details 41
2.1. Preparation and Characterization of graphite flake-loaded BFRPs 41
2.1.1. Materials 41
2.1.2. Fabrication of NGF/CF/epoxy composites 41
2.1.3. Characterization and testing of NGB composites 43
2.2. Preparation and Characterization of Carbon black-loaded CFRPs 45
2.2.1. Materials 45
2.2.2. Ozone treatment of CBs 46
2.2.3. Fabrication of OCBs/CF/epoxy composites 46
2.2.4. Characterization and testing of OCE composites 47
2.3. Preparation and Characterization of graphite nanofiber-loaded epoxy composites 50
2.3.1. Materials 50
2.3.2. Surface modification of GNFs 50
2.3.3. Fabrication of GNF/epoxy composites 51
2.3.4. Characterization and testing of GNF/epoxy composites 52
2.4. Preparation and Characterization of graphene oxide/graphite nanofiber-loaded CFRPs 55
2.4.1. Materials 55
2.4.2. Synthesis of graphene oxide 56
2.4.3. Synthesis of GO-GNF nanohybrids 57
2.4.4. Fabrication of GO-GNF/CF/epoxy composites 58
2.4.5. Characterization and testing of GO-GNF/CF/epoxy composites 59
2.5. Preparation and Characterization of graphitic carbon nitride/nanodiamond hybrid composites 62
2.5.1. Materials 62
2.5.2. Preparation of graphitic carbon nitride 62
2.5.3. Preparation of g-C₃N₄/ND hybrid composites 63
2.5.4. Characterization of g-C₃N₄/ND hybrid composites 63
Chapter 3. Results and Discussion 66
3.1. Interfacial behavior of NGB composites 66
3.1.1. Interfacial properties of NGB composites 66
3.1.2. Thermal conductivity of NGB composites 67
3.1.3. Thermal stability of NGB composites 70
3.1.4. Fracture toughness of NGB composites 72
3.2. Interfacial behavior of OCE composites 74
3.2.1. Characterization of OCBs 74
3.2.2. Morphology of OCBs 77
3.2.3. Interfacial properties of OCE composites 78
3.2.4. Fracture toughness of OCE composites 80
3.3. Interfacial behavior of TGNF composites 83
3.3.1. Characterization of TGNFs 83
3.3.2. Morphology of TGNFs 85
3.3.3. Interfacial properties of TGNF composites 87
3.3.4. Fracture resistance of TGNF composites 89
3.4. Interfacial behavior of GO-GNF composites 92
3.4.1. Characterization of GO-GNFs 92
3.4.2. Morphologies of GO-GNFs 95
3.4.3. Interfacial properties of GO-GNF composites 97
3.4.4. Fracture toughness of GO-GNF composites 100
3.5. Interfacial behavior of g-C₃N₄/ND hybrid composites 104
3.5.1. Characterization of g-C₃N₄/ND hybrid composites 104
3.5.2. Morphology of g-C₃N₄/ND hybrid composites 107
3.5.3. Interfacial properties of g-C₃N₄/ND hybrid composites 108
3.5.4. Optical properties of g-C₃N₄/ND hybrid composites 111
Chapter 4. Conclusions and outlook 114
References 117
Table 1. Formulations of NGF/BFs/epoxy composites. 42
Table 2. Surface free energy of the test wetting liquids used. 45
Table 3. Surface free energy of NGB composites. 67
Table 4. DCAs of the composites. 99
Table 5. The contact angles of the g-C₃N₄/ND hybrid composites. 110
Figure 1. Global consumption composition of epoxy resin by sector demand. 21
Figure 2. Schematic illustrations of curing mechanism. 22
Figure 3. Schematic illustrations of epoxy-based composite interfaces. 25
Figure 4. Schematic illustrations of bridging incident in epoxy-based composites. 27
Figure 5. Schematic illustrations of the relationship between contact angle and wettability. 29
Figure 6. Schematic illustrations of the thermal conduction mechanism: (a) amorphous polymers, and (b) ideal crystal structure. 34
Figure 7. Schematic illustrations of the thermal conduction mechanism: (a) epoxy-based composites loaded fillers with a continuous filler network, and (b) discontinuous filler network. 36
Figure 8. Schematic illustrations of the bridging and pull-out due to fillers. 39
Figure 9. Schematic illustrations of the NGF/CF/epoxy composites preparation process. 42
Figure 10. Schematic illustrations of the OCB/CF/epoxy composites preparation process. 47
Figure 11. Schematic illustrations showing (a) the surface modifications of the GNFs, and (b) the preparation process for the GNF/epoxy composites. 52
Figure 12. Surface morphology of GO: (a) SEM images of GO and (b) TEM images of GO. 56
Figure 13. Schematic representation of the GO-GNF/CF/epoxy composites: (a) synthesis of the GO-GNF nanohybrids, (b) the preparation of the composites. 59
Figure 14. Schematic representation of the g-C₃N₄/ND hybrid composites. 63
Figure 15. Thermal conductivity of NGB composites: (a) thermal conductivity, and (b) temperature change curve over time. 69
Figure 16. Thermal stability of the NGB composites: (a) TGA, (b) first-derivative TGA, (c) Plot of ln (ln(1-α)⁻¹) versus, (d) pyrolysis activation energy. 71
Figure 17. Fracture toughness of the NGB composites: (a) KIC and (b) GIC.[이미지참조] 73
Figure 18. Characterization of OCB: (a) XRD, (b) FT-IR, and (c) high-resolution XPS spectra. 75
Figure 19. Characterization of OCB: (a) C 1s and (b) O 1s core level XPS spectra. 76
Figure 20. Surface morphology of OCB: respective FE-TEM images (a), (b) and particle-size distributions (c), (d). 78
Figure 21. Interfacial properties of the OCE composites: (a) surface free energy, (b) ILSS. 80
Figure 22. Mechanical properties of the CCE and OCE composites: (a) KIC, (b) load-deflection curves.[이미지참조] 82
Figure 23. Characterizations of TGNFs: (a) XRD, (b) XPS full survey spectra, (c) C₁ₛ core-level of XPS spectra, (d) N₁ₛ core-level of XPS spectra for TGNF, and (e) chemical reactions... 85
Figure 24. Surface morphologies of the TGNFs: (a) TEM images of bare GNF, (b) AGNF, (c) TGNF, and (d-f) particle distributions of the GNF prepared in the study. 87
Figure 25. Interfacial properties of the TGNF composites: (a) surface free energy, (b) polar component, and (c) optical images of the wetting behaviors of distilled water over time. 89
Figure 26. Mechanical properties of the TGNF composites: (a) KIC and (b) GIC.[이미지참조] 90
Figure 27. Schematic illustrations of fracture mechanisms. 91
Figure 28. Characterization of GO-GNFs: (a) XRD, (b) FT-IR spectra, (c) high-resolution XPS spectra, and (d), (e) C 1s core level of XPS spectra. 95
Figure 29. Surface morphology of GO-GNFs: (a) TEM images of GNFs, (b) OGNFs, (c) GO-GNFs, (d) sedimentation behavior in distilled water and particle-size distributions of GNFs, (e)... 97
Figure 30. Interfacial properties of GO-GNF composites: (a) surface free energy, (b) polar component and (c) optical images of the wetting behavior of distilled water over time. 100
Figure 31. Mechanical properties of GO-GNF composites: (a) ILSS, (b) KIC, (c) load-deflection curves and (d) fracture mechanisms.[이미지참조] 102
Figure 32. Fracture surfaces of GO-GNF composites: (a) 0.8 wt% GNF composites, (b) 0.8 wt% OGNF composites, and (c) 0.8 wt% GO-GNF composites. (d), (e), and (f) are the... 104
Figure 33. Characterization of the g-C₃N₄/ND hybrid composites: (a) XRD, (b) XPS survey, (c) C1s core-level of XPS spectra, (d) N1s core-level of XPS spectra. 106
Figure 34. Surface morphology of the g-C₃N₄/ND hybrid composites: (a) SEM images of g-C₃N₄, (b) g-C₃N₄/ND-1.0 wt%, (c) g-C₃N₄/ND-3.0 wt%, (d) TEM images of g-C₃N₄, (e) g-... 108
Figure 35. Interfacial properties of the g-C₃N₄/ND hybrid composites: (a) N₂/77 K adsorption/desorption isotherms and pore size distribution, (b) surface free energy. 110
Figure 36. Optical properties of the g-C₃N₄/ND hybrid composites: (a) UV-vis DRS spectra and (b) corresponding plots of (ahv)¹/² versus photon energy (hv).[이미지참조] 112
Figure 37. Photocatalytic activity of the Rh B on g-C₃N₄/ND hybrid composites: (a) photodegradation performance of the Rh B under simulated solar light irradiation and (b)... 113