본 연구의 목적은 천연다당류 잔탄검과 O/W형 에멀젼 식품계의 마요네즈 및 달팽이점액여과추출물과 이를 사용한 화장품의 실제 적용 상황과 유사하게 설계된 다양한 유동장 하에서 발생하는 유변학적 특성을 파악하고, 나아가 대진폭 진동전단 변형하에서의 비선형 점탄성 거동을 체계적으로 분석하기 위하여 근사적 방법 및 ...
본 연구의 목적은 천연다당류 잔탄검과 O/W형 에멀젼 식품계의 마요네즈 및 달팽이점액여과추출물과 이를 사용한 화장품의 실제 적용 상황과 유사하게 설계된 다양한 유동장 하에서 발생하는 유변학적 특성을 파악하고, 나아가 대진폭 진동전단 변형하에서의 비선형 점탄성 거동을 체계적으로 분석하기 위하여 근사적 방법 및 Fourier transform분석법을 활용하였으며, Wagner 모델의 적용성을 검토하는 것이다. 잔탄검과 마요네즈는 응력파동 그래프과 Lissajous 곡선의 해석을 통해 비선형점탄성영역 내에서는 변형량과 응력 간의 선형성이 사라지며 일정한 주기를 갖는 비정현파 응력파형과 타원형을 벗어난 S형의 Lissajous 곡선이 나타남을 확인하였다. 또한 FFT (fast Fourier transform) 해석으로부터 비선형 점탄성 거동을 분석한 결과 선형 응답한계 이상의 대변형하에서는 3차 비선형 점탄성 함수 이상의 고차항의 영향이 크게 작용함을 확인하였다. 급개시 전단유동장에서 잔탐검의 과도적 레올러지 거동은 Wagner나 Osaki-Zapas을 통한 예측 결과보다는 Soskey-Winter 댐핑함수를 통한 결과에서 더 높은 적용성을 나타내었다. 시간-변형량 분리형 K-BKZ 구성방정식을 이용하여 마요네즈의 비선형 점탄성 거동을 분석한 결과 응력완화 스펙트럼의 수는 예측 결과에 크게 영향을 미치지 않는 것으로 나타났고, Wagner 모델 및 댐핑함수에 특정 상수 6.5 를 곱할 시 그 예측 결과는 마요네즈의 비선형 점탄성 거동을 유사하게 설명할 수 있음을 확인하였다. 달팽이점액 여과추출물을 기반으로 한 화장품은 달팽이점액 여과추출물과는 다르게 상당한 크기의 항복응력을 가졌으며 강한 Shear-thinning 거동을 나타내는 물질로 화장품을 바를 시 도포성이 좋은 물질임을 알 수 있었다. 적용범위가 넓어졌을 때와 비슷한 유동을 묘사하는 대진폭 진동 전단 유동장 하에서는 달팽이점액 여과추출물은 저장 및 손실 탄성률 모두 strong strain-overshoot 비선형 거동을 보였으며, 두 타입의 화장품은 각각 weak strain-overshoot 비선형 거동과 strain-thinning 비선형 거동을 나타내었다. 선형 점탄성 구간 내에서 변형이 가해졌을 때 전반적으로 탄성적 성질이 점성적 성질보다 우위에 있는 두 타입의 화장품과는 달리 달팽이 점액은 가해지는 각주파수에 따라 점탄성 성질이 바뀌는 구조적으로 민감한 물질임을 확인할 수 있었다. 또한, 잔탄검과 마요네즈와 마찬가지로 응력파동 그래프과 Lissajous 곡선의 해석을 통해 비정현파 응력파형과 S형의 Lissajous 곡선이 나타남을 확인하였고 FT 해석을 통해 비선형성이 강해질수록 고차항 비선형 점탄성 함수를 반드시 고려하여야 함을 확인하였다.
본 연구의 목적은 천연다당류 잔탄검과 O/W형 에멀젼 식품계의 마요네즈 및 달팽이점액여과추출물과 이를 사용한 화장품의 실제 적용 상황과 유사하게 설계된 다양한 유동장 하에서 발생하는 유변학적 특성을 파악하고, 나아가 대진폭 진동전단 변형하에서의 비선형 점탄성 거동을 체계적으로 분석하기 위하여 근사적 방법 및 Fourier transform 분석법을 활용하였으며, Wagner 모델의 적용성을 검토하는 것이다. 잔탄검과 마요네즈는 응력파동 그래프과 Lissajous 곡선의 해석을 통해 비선형점탄성영역 내에서는 변형량과 응력 간의 선형성이 사라지며 일정한 주기를 갖는 비정현파 응력파형과 타원형을 벗어난 S형의 Lissajous 곡선이 나타남을 확인하였다. 또한 FFT (fast Fourier transform) 해석으로부터 비선형 점탄성 거동을 분석한 결과 선형 응답한계 이상의 대변형하에서는 3차 비선형 점탄성 함수 이상의 고차항의 영향이 크게 작용함을 확인하였다. 급개시 전단유동장에서 잔탐검의 과도적 레올러지 거동은 Wagner나 Osaki-Zapas을 통한 예측 결과보다는 Soskey-Winter 댐핑함수를 통한 결과에서 더 높은 적용성을 나타내었다. 시간-변형량 분리형 K-BKZ 구성방정식을 이용하여 마요네즈의 비선형 점탄성 거동을 분석한 결과 응력완화 스펙트럼의 수는 예측 결과에 크게 영향을 미치지 않는 것으로 나타났고, Wagner 모델 및 댐핑함수에 특정 상수 6.5 를 곱할 시 그 예측 결과는 마요네즈의 비선형 점탄성 거동을 유사하게 설명할 수 있음을 확인하였다. 달팽이점액 여과추출물을 기반으로 한 화장품은 달팽이점액 여과추출물과는 다르게 상당한 크기의 항복응력을 가졌으며 강한 Shear-thinning 거동을 나타내는 물질로 화장품을 바를 시 도포성이 좋은 물질임을 알 수 있었다. 적용범위가 넓어졌을 때와 비슷한 유동을 묘사하는 대진폭 진동 전단 유동장 하에서는 달팽이점액 여과추출물은 저장 및 손실 탄성률 모두 strong strain-overshoot 비선형 거동을 보였으며, 두 타입의 화장품은 각각 weak strain-overshoot 비선형 거동과 strain-thinning 비선형 거동을 나타내었다. 선형 점탄성 구간 내에서 변형이 가해졌을 때 전반적으로 탄성적 성질이 점성적 성질보다 우위에 있는 두 타입의 화장품과는 달리 달팽이 점액은 가해지는 각주파수에 따라 점탄성 성질이 바뀌는 구조적으로 민감한 물질임을 확인할 수 있었다. 또한, 잔탄검과 마요네즈와 마찬가지로 응력파동 그래프과 Lissajous 곡선의 해석을 통해 비정현파 응력파형과 S형의 Lissajous 곡선이 나타남을 확인하였고 FT 해석을 통해 비선형성이 강해질수록 고차항 비선형 점탄성 함수를 반드시 고려하여야 함을 확인하였다.
The first objective is to quantitatively characterize the nonlinear rheological behavior of concentrated xanthan gum systems in LAOS and start-up shear flow fields by means of stress waveform, Lissajous pattern analysis, Fourier transform (FT) rheology and Wagner constitutive equation. The main find...
The first objective is to quantitatively characterize the nonlinear rheological behavior of concentrated xanthan gum systems in LAOS and start-up shear flow fields by means of stress waveform, Lissajous pattern analysis, Fourier transform (FT) rheology and Wagner constitutive equation. The main findings obtained from this study are summarized as follows: When a sinusoidal deformation with large strain amplitude is applied, a distorted and nonsinusoidal but symmetrical stress response waveform is observed with time. A saw-tooth shaped stress signal detected at large strain amplitudes may arise from a unique microstructure of xanthan polymer chains. At relatively small strain amplitudes, the Lissajous patterns show an elliptical form. When larger strain amplitudes are applied, however, the Lissajous patterns are noticeably nonelliptical with exhibiting a characteristic “S” shape. In order to interpret the complicated nonlinear viscoelastic behavior occurring at large deformations, the fundamental terms as well as the higher harmonics of phase angles defined at the odd terms should be deliberated for a quantitatively advanced analysis. The Wagner model adopting the Wagner damping function exhibits a superior performance to the Wagner model adopting the Soskey-Winter damping function for predicting the whole steps of a transient rheological behavior, even though the Soskey-Winter damping function shows a better ability than the Wagner damping function to describe the damping behavior of concentrated xanthan gum systems. The second objective of the present study is to systematically compare and characterize the nonlinear rheological behavior of three different types of commercial mayonnaises in LAOS flow fields by means of stress waveform, Lissajous pattern analysis, Fourier transform (FT) rheology and time-strain separable K-BKZ constitutive equation. The main findings obtained from this study are summarized as follows: When larger strain amplitudes are applied, a distorted and nonsinusoidal but symmetrical stress response waveform is observed and the Lissajous patterns are noticeably nonelliptical, and furthermore, as the strain amplitude is more increased, the tips of loops become more pointed with exhibiting a distinctive sigmoid shape. In a linear viscoelastic behavior regime, only fundamental stress amplitude is existed at a calculated frequency of 1rad/s, however, when larger strain amplitudes are applied, the nonlinear viscoelastic functions from first to seventh (or ninth) harmonic terms must be considered for an accurate analysis. By multiplying a specific constant of 6.5, the effect of damping functions on the predictive ability of the Wagner model is more sensitive than that of memory functions. The Wagner model predictions adopting the equations of Zapas, Soskey-Winter, modified Zapas and modified Soskey-Winter damping functions are closely agreement with the experimental results in the nonlinear viscoelastic region. The third objective of this study has been to systematically compare and characterize the linear rheological behavior of snail secretion filtrate (SSF) and SSF-based cosmetic products in various shear flow fields. The main findings obtained from this study are summarized as follows: Unlike snail secretion filtrate, SSF-based gel and SSF-based cream are regarded as a viscoplastic material having a finite magnitude of yield stress. Snail secretion filtrate and SSF-based cosmetic products exhibit a pronounced non-Newtonian shear-thinning flow behavior. The Casson, Mizrahi-Berk, Heinz-Casson and Herschel-Bulkley models are all applicable and have almost an equivalent ability to quantitatively describe the steady shear flow behavior of both SSF-based gel and SSF-based cream. The linear viscoelastic behavior of the snail secretion filtrate varies according to the frequency of the applied angular frequency, on the other hand, that of SSF-based cosmetic products are dominated by an elastic nature rather than a viscous nature. The nonlinear viscoelastic behavior of snail secretion filtrate at large strain amplitudes belongs to Type IV (strong strain-overshoot). SSF-based gel which is shown the similar behavior of snail secretion filtrate, is affiliated to Type III (weak strain-overshoot), whereas SSF-based cream is Type I (strain-thinning). At relatively larger strain amplitudes are applied, otherwise, the normalized Lissajous patterns (reduced stress-reduced strain rate loop) are noticeably nonelliptical, and the tips of loops become more pointed with demonstrating a distinctive sigmoid shape. And, the nonlinear viscoelastic functions from first to seventh (or ninth) harmonic terms must be considered for an accurate analysis.
The first objective is to quantitatively characterize the nonlinear rheological behavior of concentrated xanthan gum systems in LAOS and start-up shear flow fields by means of stress waveform, Lissajous pattern analysis, Fourier transform (FT) rheology and Wagner constitutive equation. The main findings obtained from this study are summarized as follows: When a sinusoidal deformation with large strain amplitude is applied, a distorted and nonsinusoidal but symmetrical stress response waveform is observed with time. A saw-tooth shaped stress signal detected at large strain amplitudes may arise from a unique microstructure of xanthan polymer chains. At relatively small strain amplitudes, the Lissajous patterns show an elliptical form. When larger strain amplitudes are applied, however, the Lissajous patterns are noticeably nonelliptical with exhibiting a characteristic “S” shape. In order to interpret the complicated nonlinear viscoelastic behavior occurring at large deformations, the fundamental terms as well as the higher harmonics of phase angles defined at the odd terms should be deliberated for a quantitatively advanced analysis. The Wagner model adopting the Wagner damping function exhibits a superior performance to the Wagner model adopting the Soskey-Winter damping function for predicting the whole steps of a transient rheological behavior, even though the Soskey-Winter damping function shows a better ability than the Wagner damping function to describe the damping behavior of concentrated xanthan gum systems. The second objective of the present study is to systematically compare and characterize the nonlinear rheological behavior of three different types of commercial mayonnaises in LAOS flow fields by means of stress waveform, Lissajous pattern analysis, Fourier transform (FT) rheology and time-strain separable K-BKZ constitutive equation. The main findings obtained from this study are summarized as follows: When larger strain amplitudes are applied, a distorted and nonsinusoidal but symmetrical stress response waveform is observed and the Lissajous patterns are noticeably nonelliptical, and furthermore, as the strain amplitude is more increased, the tips of loops become more pointed with exhibiting a distinctive sigmoid shape. In a linear viscoelastic behavior regime, only fundamental stress amplitude is existed at a calculated frequency of 1rad/s, however, when larger strain amplitudes are applied, the nonlinear viscoelastic functions from first to seventh (or ninth) harmonic terms must be considered for an accurate analysis. By multiplying a specific constant of 6.5, the effect of damping functions on the predictive ability of the Wagner model is more sensitive than that of memory functions. The Wagner model predictions adopting the equations of Zapas, Soskey-Winter, modified Zapas and modified Soskey-Winter damping functions are closely agreement with the experimental results in the nonlinear viscoelastic region. The third objective of this study has been to systematically compare and characterize the linear rheological behavior of snail secretion filtrate (SSF) and SSF-based cosmetic products in various shear flow fields. The main findings obtained from this study are summarized as follows: Unlike snail secretion filtrate, SSF-based gel and SSF-based cream are regarded as a viscoplastic material having a finite magnitude of yield stress. Snail secretion filtrate and SSF-based cosmetic products exhibit a pronounced non-Newtonian shear-thinning flow behavior. The Casson, Mizrahi-Berk, Heinz-Casson and Herschel-Bulkley models are all applicable and have almost an equivalent ability to quantitatively describe the steady shear flow behavior of both SSF-based gel and SSF-based cream. The linear viscoelastic behavior of the snail secretion filtrate varies according to the frequency of the applied angular frequency, on the other hand, that of SSF-based cosmetic products are dominated by an elastic nature rather than a viscous nature. The nonlinear viscoelastic behavior of snail secretion filtrate at large strain amplitudes belongs to Type IV (strong strain-overshoot). SSF-based gel which is shown the similar behavior of snail secretion filtrate, is affiliated to Type III (weak strain-overshoot), whereas SSF-based cream is Type I (strain-thinning). At relatively larger strain amplitudes are applied, otherwise, the normalized Lissajous patterns (reduced stress-reduced strain rate loop) are noticeably nonelliptical, and the tips of loops become more pointed with demonstrating a distinctive sigmoid shape. And, the nonlinear viscoelastic functions from first to seventh (or ninth) harmonic terms must be considered for an accurate analysis.
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