탄소 입자 함유 재료의 유변학적 특성과 임피던스 특성 간의 상관관계

다국어 초록 (Multilingual Abstract)

Carbon particles embedded materials are widely used in applications such as battery slurries, conductive coatings, and polymer composites, where both processability and electrochemical performance are governed by their internal structures. Under the flow conditions, the internal structures of these materials continuously evolves, causing simultaneous changes in rheological behavior and impedance response. Therefore, investigating the correlation between rheological and impedance properties under such flow conditions is essential for evaluating internal structural changes in these materials. In this study, rheological measurements and electrochemical impedance spectroscopy (EIS) were employed to analyze this correlation and to evaluate internal structural changes in carbon particles embedded materials. In Chapter II, an in-line evaluation method for a graphite-based conductive suspension is established using a pipe-flow system. Rheological measurements were used to analyze shear-thinning and thixotropic behavior, while X-ray diffraction and scanning electron microscopy were employed to confirm flow-induced particle orientation. The impedance spectra measured at different flow rates confirmed that particle orientation affects the effective conduction path. The internal structure changes of the graphite suspension under flow conditions were quantitatively evaluated through equivalent circuit analysis and numerical simulation. In Chapter III, The relationship between the formation of conductive networks in PP/CB composites and their rheological, impedance, and processing properties was investigated as a function of carbon black content and shear rate. Steady shear and frequency sweep tests reveal the transition from liquid-like to solid-like viscoelastic behavior associated with the development of a percolated CB network, which is supported by scanning electron microscopy. The formation and changes in the conductive path within the composite were confirmed through the impedance response as a function of filler content and deformation. Injection molding simulations revealed that the CB network formed within the composite material increases flow resistance and filling pressure.

목차 (Table of Contents)

• Ⅰ. Introduction 1
• 1.1 Research backgrounds 1
• 1.2 Objectives of present work 3
• ⅠI. Rheological and Impedance Analysis for In-Line Evaluation of Internal Structure of Carbon Suspension 5
• 2.1 Introduction 5
• 2.2 Experimental 8
• 2.2.1 Materials and sample preparation 8
• 2.2.2 Rheological characterization 8
• 2.2.3 Morphological analysis 8
• 2.2.4 Electrochemical characterization under the pipe flow 9
• 2.2.5 Numerical analysis of flow field and particle orientation 10
• 2.3. Results and discussion 11
• 2.3.1 Rheological characterization 11
• 2.3.1.1 Steady-state shear test 11
• 2.3.1.2 Three-interval thixotropy test 13
• 2.3.2 Morphological analysis 15
• 2.3.3 Electrochemical characterization under the pipe flow 17
• 2.3.3.1 Nyquist plot and frequency-dependent plot 17
• 2.3.3.2 Bode plots of impedance magnitude and phase angle 20
• 2.3.3.3 Electrochemical equivalent circuit analysis 22
• 2.3.4 Numerical analysis of flow field and particle orientation 25
• 2.4 Conclusion 28
• Ⅲ. Investigation of Internal Structure of Carbon Embedded Composite via Impedance and Rheological Analysis 29
• 3.1 Introduction 29
• 3.2 Experimental 32
• 3.2.1 Materials and sample preparation 32
• 3.2.2 Rheological characterization 32
• 3.2.3 Morphological analysis 32
• 3.2.4 Electrochemical characterization under the shear deformation 33
• 3.2.5 Numerical analysis of injection molding 34
• 3.3 Results and discussion 36
• 3.3.1 Rheological characterization 36
• 3.3.1.1 Steady-state shear test 36
• 3.3.1.2 Frequency sweep test 37
• 3.3.2 Morphological analysis 39
• 3.3.3 Electrochemical characterization under the shear deformation 41
• 3.3.3.1 Nyquist plots with different CB contents 41
• 3.3.3.2 Conductivity as a function CB contents 43
• 3.3.3.3 Nyquist plots with different shear rate 45
• 3.3.3.4 Bode plots of impedance magnitude at different shear rates 47
• 3.3.3.5 Bode plots of imaginary impedance at different shear rates 49
• 3.3.3.6 Electrochemical equivalent circuit analysis 51
• 3.3.3.7 Resistance as a function of carbon black content 53
• 3.3.3.8 Resistance as a function of shear rate 53
• 3.3.4 Numerical analysis of injection molding 56
• 3.3.4.1 Melt front time distribution 56
• 3.3.4.2 Filling pressure distribution and sprue pressure variation 56
• 3.4 Conclusions 58
• Ⅳ. Conclusion 59
• Reference 61
• 국문 초록 68