탄소기반 필러를 함유한 endo-dicyclopentadiene/ethylidene norbornene 복합체의 특성분석

다국어 초록 (Multilingual Abstract)

Carbon fiber reinforced thermosetting polymer composites were fabricated and characterized in this study. Endo-dicyclopentadiene (endo-DCPD), ethylidene norbornene (ENB), and their blends were used as matrix resins and multi-walled carbon nanotube (MWNT), carbon nanofiber (CNF), and short carbon fiber (SCF) were as reinforcements. The matrix resins were cured via the ring-opening metathesis polymerization (ROMP) reaction in the presence of the 1st generation and 2nd generation Grubbs' catalysts. To understand ROMP mechanisms of the matrix resins under the two different catalysts, the resins were analyzed using fourier transform infrared spectroscopy and differential scanning calorimetry (DSC) during curing. It revealed that the ROMP mechanism involved in the reaction system strongly depends on the type of the Grubbs' catalysts used.
DSC dynamic scans showed that ROMP reaction is accelerated with increase of ENB ratio in the endo-DCPD/ENB blends. Thermal/mechanical properties from tensile and dynamic mechanical measurements were decreased in the higher ENB ratios of the blends. This is because addition of linear/branched molecules of polyENB into highly crosslinked polyDCPD lower overall crosslinking density.
Thermal and mechanical properties of the resins incorporated with MWNT, CNF, and SCF in different loadings were investigated in this work. As a result, SCF-based composites showed a large increase in tensile modulus by about 100 % at a 20 wt% SCF loading. However, elongation-at-break and tensile toughness were greatly reduced. For MWNT-based composites, elongation-at-break and tensile toughness were increased up to a 0.4 wt% MWNT loading by about 22 % and then decreased at 0.8 wt% MWNT. The reduction of the properties is due to the aggregation of MWNT within matrix at higher loadings. Incorporation of CNF into the resins led to reduction in mechanical properties. For the all fillers used in this work, the 1st generation catalyst systems exhibited superior in tensile toughness to the 2nd generation systems. The effects of Grubbs' catalysts and blending ratios of endo-DCPD and ENB on gel fraction and swell behavior were also examined and the dispersity and interfacial adhesion of the fillers were observed using FE-SEM.
In addition, polypropylene (PP) composites containing conductive MWNT (multi-walled carbon nanotube) and SSF (stainless steel short fiber) were manufactured using a twin screw extruder and characterized their surface resistivity and mechanical properties in this work. Surface resistivity measurements showed that the percolation threshold appeared at a lower MWNT loading when a small amount of SSF was added to PP/MWNT composites. Tensile modulus and strength of the composites increased but elongation-at-break decreased greatly compared to pure PP. Also, effects of MWNT and SSF on storage modulus and tan δ from dynamic mechanical analysis for the composites were examined, and morphologies of fractured surface and the fillers were observed using SEM.

목차 (Table of Contents)

• 제 1 장 Endo-DCPD/ENB 블랜드 수지의 열적·기계적 특성분석 1
• 1.1 서 론 1
• 1.1.1 Endo-dicyclopentadiene(endo-DCPD) 수지 1
• 1.1.2 5-ethylidene-2-norbornene(ENB) 수지 1
• 1.1.3 Endo-DCPD와 ENB의 블랜드 3
• 1.2 실 험 3
• 1.2.1 시료 3
• 1.2.2 측정 및 분석 5
• 1) FT-IR 분석 5
• 2) DSC 측정 8
• 3) 인장 특성 8
• 4) 동역학 거동 8
• 5) 팽윤비 및 젤 분율 10
• 6) 열적 저항 측정 10
• 7) 형태학적 분석 10
• 1.3 결과 및 토론 12
• 1.3.1 FT-IR을 이용한 endo-DCPD의 경화과정 분석 12
• 1.3.2 DSC를 이용한 동적 경화 과정분석 16
• 1.3.3 인장 특성 20
• 1) 촉매 함량을 달리한 poly-DCPD 시험편분석 20
• 2) Endo-DCPD/ENB 블랜드의 경화 시험편분석 24
• 1.3.4 동역학적 특성 28
• 1) 촉매 함량을 달리한 poly-DCPD 시험편분석 28
• 2) Endo-DCPD/ENB 블랜드의 경화 시험편분석 28
• 1.3.5 팽윤비 및 젤 분율 33
• 1) 촉매 함량을 달리한 poly-DCPD 시험편분석 33
• 2) Endo-DCPD/ENB 블랜드의 경화 시험편분석 38
• 1.3.6 열 안정성 41
• 1.3.7 파단면 관찰 41
• 1.4 결론 47
• [참고 문헌] 49
• 제 2 장 탄소기반 필러를 함유한 endo-dicyclopentadiene 복합소재의 열적·기계적 특성분석 51
• 2.1 서론 51
• 2.2 실험 59
• 2.2.1 Grubbs 촉매의 재결정 59
• 2.2.2 탄소기반 필러의 분산 59
• 2.2.3 복합소재 시험편 제조 61
• 2.2.4 측정 및 분석 61
• 1) 인장 특성 61
• 2) 동역학 거동 63
• 3) 형태학적 분석 63
• 2.3 결과 및 토론 64
• 2.3.1 인장 특성 64
• 1) 탄소 단섬유(SCF) 64
• 2) 다중벽 탄소 나노튜브(MWNT) 64
• 3) 탄소 나노섬유(CNF) 69
• 2.3.2 동역학 특성 분석 75
• 1) SCF 75
• 2) MWNT 75
• 2.3.3 형태학적 분석 80
• 2.4 결론 84
• [참고 문헌] 85
• 제 3 장 탄소나노튜브와 스테인레스강 단섬유를 함유한 폴리프로필렌 복합체의 전기저항 및 기계적 특성 88
• 3.1 서론 88
• 3.2 실험 90
• 3.2.1 복합 펠렛의 제조 90
• 3.2.2 표면저항 측정용 시험편 제작 90
• 3.2.3 인장 및 동역학적 특성 측정용 시험편 제작 92
• 3.2.4 측정 및 분석 92
• 1) 표면 저항 92
• 2) 인장 특성 92
• 3) 동역학적 특성 92
• 4) 모폴로지 93
• 3.3 결과 및 토론 94
• 3.3.1 전기저항 측정 94
• 1) 볼밀 효과 94
• 2) MWNT의 함량변화 94
• 3) SSF의 함량변화 97
• 3.3.2 인장 특성 97
• 3.3.3 동역학적 분석 101
• 3.3.4 모폴로지 관찰 101
• 1) MWNT의 전처리 효과 101
• 2) MWNT/SSF 복합체 파단면 105
• 3.4 결론 109
• [참고 문헌] 110