생분해성 바이오 에폭시 기반 DGEBA/ESBO/마이크로 실리카 복합체의 배전용 절연소재 적용을 위한 수분 흡습 및 건조 신뢰성 평가 = Moisture Absorption and Drying Reliability Evaluation for Application of Biodegradable Bio-epoxy-Based DGEBA/ESBO/Micro Silica Composites for Insulation Materials in Power Distribution

다국어 초록 (Multilingual Abstract)

The international community's efforts to reduce greenhouse gases, a global environmental problem, are continuing, and bio-epoxy resin, a sustainable and renewable resource, is being proposed as part of this effort. The number of researchers producing eco friendly bio-epoxy resins using various types of vegeTable oils is increasing. Among many vege Table oils, soybean oil is relatively cheap and flexible, and epoxidized soybean oil (ESBO) is attracting attention as an ecofriendly insulating material that is very necessary for carbon neutrality of heavy electric distribution equipment. For that reason, this study conducted research on environmentally friendly biodegradability and the reliability of bio-epoxy as an insulating material for heavy electrical equipment to replace petrochemical epoxy through moisture absorption and drying processes. First, a biodegradable epoxy thermo setting resin was prepared by mixing bis-phenol A diglycidyl ether (DGEBA) and epoxidized soybean oil (ESBO), and its biodegradability and electrical and mechanical properties were studied. For biodegradability studies, DGEBA:ESBO epoxy mixtures were used in ratios of 100/0, 90/10, 80/20, 70/30, 60/40, and 50/50, respectively. In the soil burial test, as the ESBO content increased, the DGEBA:ESBO thermoset decomposed into smaller pieces over 4 to 6 months, whereas the DGEBA thermoset without ESBO maintained the same shape for the 8-month bio-degradation study period. Cross linking density was analyzed using the solvent swelling method and the Flory-Rehner equation. Characteristic tests for biodegradability research were conducted on mechanical tensile and flexural strength characteristics, and electrical insulation breakdown (HVAC, HVDC) characteristics. Then, experiments were conducted on cross linking density and glass transition temperature, and as a result, the highest results were obtained for the DGEBA:ESBO (around 80/20) thermo setting resin. Second, epoxy resin absorbs moisture over a long period of time when exposed to the surrounding environment. It affects a variety of application fields ranging from high voltage-based heavy electrical equipment and electronic components. A sample filled with micro silica_65wt% in a composite mixed with bio-epoxy to replace heavy electric equipment for distribution, that is, DGEBA:ESBO=100/0, 90/10, 80/20, 70/30, 60/40, 50/50/M10_65wt%, was prepared. The moisture absorption was immersed for 735 hours at 95℃, and the drying process was performed in a drying oven for 318 hours at 105℃ until the sample reached a saturated state with no change in moisture evaporation. The weight % of moisture absorption and drying was obtained, and the glass transition temperature characteristics were evaluated as electrical insulation breakdown (HVAC, HVDC, dielectric properties), mechanical properties (tensile strength, flexural strength) and thermal properties of a sample (circular sample) without filling inorganic substances. In addition, the moisture absorption and dry weight %, electrical insulation breakdown (HVAC, HVDC, dielectric properties), mechanical (tensile, flexural strength) properties, and thermal (glass transition temperature) properties of the DGEBA:ESBO=Contents Ratio/M10_65wt% composite manufactured under the same conditions as the insulator manufactured by the medium-sized electrical equipment industry for power distribution were evaluated. In the case of epoxy resin (DGEBA:ESBO=100/0,70/30), a location where moisture can be absorbed and stored can exist within the free volume, and since physical bonding with water molecules is possible from the -OH (hydroxyl group) of Bis-phenol A type and the –O- oxygen atom in Epichlorohydrin, it is thought that this is a location where moisture can be stored. Since the ester group ( ) exists in excess in bio-epoxy, the moisture absorption weight has a large effect, and a water shell is formed on many inorganic substances (M10_65 wt%). Although the moisture absorption of the inorganic substances themselves is weak, the moisture absorbed from the epoxy weakens the organic/inorganic interface in the form of an electric double layer in which all inorganic substances are water shelled, and it is thought that this has an effect on the interface of all inorganic substances regardless of the DGEBA:ESBO content.

국문 초록 (Abstract)

세계적으로 환경문제인 온실가스 감축을 위한 국제사회의 노력이 지속되고 있으며, 그 일환으로 지속 가능하고 재생 가능한 자원인 바이오 에폭시 수지가 제안되고 있 다. 여러 종류의 식물성 오일을 사용하여 친환경 바이오 에폭시 수지를 제조하는 연 구자들이 증가하고 있다. 다수의 식물성 오일들 중에서도 대두 유는 가격이 비교적 싸고, 유연성을 가지고 있으며, 에폭시화된 대두유(ESBO)가 배전용 중전기기의 탄 소중립에 매우 필요한 친환경 절연 소재로 주목을 받고 있다. 그런 이유로, 본 연구 에서는 환경친화적인 생분해성에 관한 연구와 바이오 에폭시로서 석유화학 에폭시 로 대체할 중전기기 절연 소재로서 수분 흡습 및 건조과정을 통한 신뢰성에 기반한 연구를 실시하였다. 첫째, 생분해성의 에폭시 열경화성 수지는 비스페놀 A 디글리시딜 에테르 (DGEBA)와 에폭시화 ESBO를 혼합하여 제조되었으며, 생분해성과 전기적 및 기계 적 특성을 연구하였다. 생분해성 연구를 위하여 DGEBA:ESBO 에폭시 혼합물은 각 각 100/0, 90/10, 80/20, 70/30, 60/40, 50/50의 비율로 사용되었다. 토양 매몰 시 험에서 ESBO 함량이 증가함에 따라 DGEBA:ESBO 열경화성 수지는 4~6개월까지 더 작은 조각으로 분해되었지만, ESBO가 없는 DGEBA 열경화성 수지는 생분해 연 구 기간인 8개월 동안 동일한 형태를 유지하였다. 가교 밀도는 용매 팽윤법과 플로 리-레너 방정식(Flory-Rehner equation)을 이용하여 분석하였다. 생분해성 에폭시 의 특성 실험은 기계적 인장 및 굴곡강도 특성, 전기적 절연파괴(HVAC,HVDC) 특 성을 실시하였다. 그리고 가교 밀도와 유리전이 온도의 실험을 실시하였고 그 결과 DGEBA:ESBO (80/20부근) 열경화성 수지에서 가장 높은 결과를 얻게 되었다. 둘째, 에폭시 수지는 주변 환경에 노출되면 장기간에 걸쳐 수분을 흡습하게 된다. 고전압 기반 중전기기 및 전자부품에 이르기까지 다양한 응용 분야에 영향을 주게 된다. 배전용 중전기기에 대체할 바이오 에폭시와의 혼합된 컴포지트에 마이크로 실리카 _65wt%을 충 진한 샘플 즉, DGEBA:ESBO=100/0, 90/10, 80/20, 70/30, 60/40, 50/50/M10_65wt%을 제조하였다. 수분 흡습을 95℃×735hr 동안 침지하였고, 건조 과정는 105℃×318hr 동안 건조 오븐 내에서 수분의 증발 변화가 없은 포화상태까 지 건조하여 샘플을 제조하였다. 수분 흡습 및 건조의 중량 %을 구하였고, 무기물 을 충진하지 않은 샘플 (원형 샘플)의 전기적 절연파괴 (HVAC,HVDC, 유전 특성), 기계적 특성(인장강도, 굴곡강도) 그리고 열적 특성으로 유리전이 온도 특성을 평가 하였다. 또한 배전용 중전기기 산업체에서 제조된 절연물과 같은 조건하에서 제조된 DGEBA:ESBO=Contents Ratio/M10_65wt% 컴포지트의 수분 흡습 및 건조 중량%, 전기적 절연파괴(HVAC,HVDC,유전특성) 특성, 기계적 (인장, 굴곡강도) 특성, 열적 (유리전이 온도) 특성을 평가 하였다. 에폭시 원형(DGEBA:ESBO=100/0,70/30)의 경우 수분이 흡습 되어 저장할 수 있 는 위치가 자유 체적 (Free Volume) 내에 존재 할수 있고 그리고 Bisphenol-A type의 O-H(수산기:hydroxyl group)와 Epichlorohydrin(에피클로로히드린)에서 – O- 산소원자(oxygen atom)로부터 물 분자와 물리적 결합이 가능하므로 수분이 저 장할 수 있는 위치로 사료된다. 바이오 에폭시에 에스테르기 (ESTERS Group)가 과량 존재함으로 수분 흡습 중량 이 크게 작용하여 많은 무기물(M10_65wt%)에 물껍질이 형성되어 무기물 자체의 흡습은 미약하지만 에폭시로 부터 흡습 된 수분이 무기물 모두에 수분이 껍질 된 전기이중층의 형상으로 유/무기 계면의 약화를 가져와 DGEBA:ESBO 함량에 관계 없이 전 무기물의 계면에 주는 영향의 주는 것으로 사료 된다.

목차 (Table of Contents)

• ◆ Index ◆
• Index ⅰ
• List of Figures vi
• Picture table of Contents ix
• Korean Summary xvii
• ABSTRACT xix
• Ⅰ. Introduction 1
• Ⅱ. Relationship Theory 7
• 1. Material 7
• 1.1. DGEBA(Diglycidyl ether of bisphenol A) 7
• 1.2. Bio-epoxy (ESBO: Epoxidized Soybean Oil) 8
• 2. Biodegradable bio-epoxy 11
• 3. HVDC Breakdown Theory 21
• 4. Dielectric Properties 22
• 5. Moisture Absorption Reliability Evaluation 26
• 6. Weibull Plot 33
• 6.1. Estimation of Shape Parameter and Scale Parameter 33
• 6.2. Brief Representation and Meaning of Weibull Plot 35
• Ⅲ. Experiment 36
• 1. Materials 36
• 2. Specimen Preparation 37
• 3. Soil Burial Test 39
• 4. Moisture Absorption and Drying Process 39
• 5. Types of Sample 41
• 6. Measuring Devices and Evaluation ±HVDC conditions 42
• 6.1. Electrical insulation breakdown tests under HVAC and ±HVDC
• conditions 42
• 6.2. Dielectric Properties 43
• 6.3. Mechanical Tests 44
• 6.4. Measurement of Glass Transition Temperature:Tg. 45
• Ⅳ Result and Discussion 46
• 1. Study on Biodegradability Properties of DGEBA:BiO=Contents Ratio
• Buried in Soil 46
• 1.1. DGEBA:ESBO Biodegradable Weight Reduction Depending on Time
• Buried in Soil 46
• 1.2. Mechanical Properties of Biodegradable Epoxy Systems 48
• 1.3. Electrical HVAC and (±)HVDC Breakdown Strength Properties
• of Biodegradable Epoxy Systems 54
• 1) HVAC Insulation Breakdown Strength 54
• 2) ±HVDC Insulation Breakdown Strength 56
• 2. Bio-epoxy Reliability Evaluation on Moisture Absorption and
• Drying 61
• 1.1. Tensile strength, Moisture Absorption and Dry weight of
• the samples M (%) 61
• 1). DGEBA:ESBO=100phr/0phr, 70phr:30phr 61
• 2) DGEBA:ESBO=Contents Ratio (100/0, 90/10, 80/20, 70/30, 60/40,
• 50/50)/M10_65wt% Composites 63
• 1.2. Electrical HVAC Short Time Insulation Breakdown Properties 67
• 1) DGEBA:ESBO=100phr/0phr, 70phr:30phr 67
• ① Reference Sample 67
• ② Moisture Absorption Sample 71
• ③ Moisture Drying Sample 75
• 2) DGEBA:ESBO=Contents Ratio (100/0, 90/10, 80/20, 70/30,
• 60/40, 50/50)/Micro-silica_65wt% Composites :HVAC Insulation
• Breakdown Strength 78
• ① Reference Sample 78
• ② Moisture Absorption (HVAC Insulation Breakdown Strength).. 81
• ③ Moisture Drying Sample 87
• 1.3. Electrical Dielectric Properties 93
• 1) DGEBA:ESBO=Contents Ratio (100/0, 90/10, 80/20, 70/30, 60/40,
• 50/50)/Micro-silica_65wt% Composites: 93
• ① Reference Sample 94
• ■ Permittivity 94
• ■ tan δ 97
• ■ Conductivity 103
• ② Moisture Absorption Sample 104
• ■ Permittivity 106
• ■ tan δ 109
• ■ Conductivity 113
• ③ Moisture Drying Sample 115
• ■ Permittivity 115
• ■ tan δ 116
• ■ Conductivity 118
• 1.4. Mechanical Properties (Tensile Strength) 120
• 1) DGEBA:ESBO=100phr;0phr,70phr;30phr 120
• ① Reference Sample 120
• ② Moisture Absorption Sample 122
• ③ Moisture Drying Sample 124
• 2) DGEBA:ESBO=Contents Ratio (100/0, 90/10, 80/20, 70/30, 60/40,
• 50/50)/Micro-silica_65wt% Composites 126
• ① Reference Sample 126
• ② Moisture Absorption Sample 128
• ③ Moisture Drying Sample 132
• 1.5. Mechanical Properties (Flexural Strength) 135
• 1) DGEBA:ESBO=100phr/0phr,70phr:30phr Composites 135
• ① Reference Sample 135
• ② Moisture Absorption Sample 137
• ③ Moisture Drying Sample 138
• 2) DGEBA:ESBO=Contents Ratio (100/0, 90/10, 80/20, 70/30, 60/40,
• 50/50)/Microsilica_65wt% Composites 140
• ① Reference Sample 140
• ② Moisture Absorption Sample 142
• ③ Moisture Drying Sample 144
• 1.6. Thermal Properties (Glass Transition Temperature) 147
• 1) DGEBA:ESBO=100phr/0phr,70phr:30phr Composites 147
• ① Reference Sample, Moisture Absorption Sample, Moisture Drying
• Sample 147
• 2) DGEBA:ESBO=Contents Ratio (100/0, 90/10, 80/20, 70/30, 60/40,
• 50/50)/Micro-silica_65wt% Composites 153
• ① Reference Sample, Moisture Absorption Sample, Moisture Drying
• Sample 153
• Ⅴ. Conclusion 157
• References 164
• Acknowledgments clxxvii
• ◆ List of Figures ◆
• [Table 2.1] Various molar ratios of hydrogen peroxide, reaction times, and
• temperatures 9
• [Table 2.2] Physical properties of ESBO 9
• [Table 2.3] Mechanical properties of bio-epoxy resin 14
• [Table 3.1] Types of biodegradable samples 41
• [Table 3.2] Types of samples for reliability assessment (moisture
• absorption) 41
• [Table 4.1.1] Tensile Strength for Biodegradable epoxy systems with various
• DGEBA: ESBO Ratio. 48
• [Table 4.1.2] Weibull parameters of tensile strength for biodegradable
• epoxy systems. 49
• [Table 4.1.3] Flexural strength for biodegradable epoxy systems with various
• DGEBA:ESBO ratios 51
• [Table 4.1.4] Weibull parameters of flexural strength for biodegradable
• epoxy systems. 52
• [Table 4.1.5] HVAC (60Hz) insulation breakdown strengths for biodegradable
• epoxy systems with various DGEBA:ESBO 54
• [Table 4.1.6] Weibull parameters of HVAC insulation breakdown strength
• for biodegradable epoxy systems. 55
• [Table 4.1.7] (−)HVDC insulation breakdown strengths for biodegradable
• epoxy systems with various DGEBA:ESBO ratios. 57
• [Table 4.1.8] Weibull parameters of (-)HVDC insulation breakdown strength
• for biodegradable epoxy systems. 58
• [Table 4.1.9] (+)HVDC insulation breakdown strengths for biodegradable
• epoxy systems with various DGEBA:ESBO ratios. 59
• [Table 4.1.10] Weibull parameters of (+)HVDC insulation breakdown strength
• for biodegradable epoxy systems 60
• [Table 4.2.1] Samples for mechanical tensile strength DGEBA:ESBO=100/0,
• 70/30 Composites and DGEBA:ESBO=100/0,70/30/M10_65wt%
• Composites comparison of moisture absorption. 61
• [Table 4.2.2] For tensile strength DGEBA:ESBO=Contents Ratio/M10_65wt%
• Composites Hygroscopic weight of the sampl 64
• [Table 4.3.1] Weibull plot characteristic parameters 67
• [Table 4.3.2] Weibull plot characteristic parameters 72
• [Table 4.3.3] Weibull plot characteristic parameters 76
• [Table 4.3.4] Weibull plot characteristic parameters 78
• [Table 4.3.5] Weibull plot characteristic parameters 83
• [Table 4.3.6] Comparison of Scale Parameters in (Reference) and Table
• 4-3-5 (Absorption 84
• [Table 4.3.7] Weibull plot characteristic parameters 89
• [Table 4.3.8] Reference, Moisture Absorption, Moisture Drying Sample of
• HVAC insulation breakdown strength Weibull plot scale parameter
• (63.2%) 90
• [Table 4.4.1] DGEBA:ESBO=content-specific/M10_65wt% composite
• dielectric constant characteristics (Reference Sample) 94
• [Table 4.4.2] DGEBA:ESBO=Contents Ratio/M10_65wt% Composite
• Dielectric Loss Characteristics Table (Reference Sample) 100
• [Table 4.4.3] DGEBA:ESBO=Contents Ratio/M10_65wt% Composites
• Permittivity result(Moisture Absorption Sample) 106
• [Table 4.5.4] DGEBA:ESBO=Contents Ratio/M10_65wt% Composites
• Dielectric loss characteristics of (Moisture Absorption Sample)
• 112
• [Table 4.4.5] DGEBA:ESBO=Contents Ratio/M10_65wt% Composites
• Dielectric constant characteristics (Moisture Drying Sample )..116
• [Table 4.4.6] DGEBA:ESBO=Contents Ratio/M10_65wt% Composites Dielectric
• loss characteristics (Moisture Drying Sample) 117
• [Table 4.5.1] Weibull plot characteristic parameters in Fig 4-5-1 120
• [Table 4.5.2] Weibull plot characteristic parameters in Fig 4-5-2 123
• [Table 4.5.3] Weibull plot characteristic parameters in Fig 4-5-4 126
• [Table 4.5.4] Weibull plot characteristic parameters in Fig 4-5-6 127
• [Table 4.5.5] Weibull plot characteristic parameters in Fig 4-5-9 ·· 129
• [Table 4.5.6] Weibull plot scale parameter (63.2%) in Fig 4-5-12 133
• [Table 4.6.1] Weibull plot characteristic parameters in Fig 4-6-1 135
• [Table 4.6.2] Weibull plot characteristic parameters in Fig 4-6-2 137
• [Table 4.6.3] Weibull plot characteristic parameters in Fig 4-6-3 139
• [Table 4.6.4] Weibull plot characteristic parameters in Fig 4-6-4 140
• [Table 4.6.5] Weibull plot characteristic parameters in Fig 4-6-7 143
• [Table 4.6.6] Weibull plot characteristic parameters in Fig 4-6-10 ·· 145
• [Table 4.7.1] Glass transition temperature in Fig 4-7-1 147
• [Table 4.7.2] Glass transition temperature in Fig 4-7-2 153