Shear and longitudinal viscosity of non-ionic C12E8 aqueous solutions
G D'Arrigo1, G Briganti, M Maccarini
1INFM, Dipartimento di Energetica, Università di Roma La Sapienza, Via A. Scarpa 16, 00161 Roma, Italy. giovanni.darrigo@uniroma1.it
The Journal of Physical Chemistry. B
|March 11, 2006
Summary
This study reveals distinct structural properties in C12E8 surfactant solutions, showing glass-like behavior in concentrated regions and complex aggregate formation in dilute areas, impacting their viscoelastic properties.
Area of Science:
- Physical Chemistry
- Materials Science
- Soft Matter Physics
Background:
- Non-ionic surfactants like C12E8 form complex structures in aqueous solutions.
- Understanding these structures is crucial for applications in various industries.
- Previous studies suggest concentration-dependent structural transitions.
Purpose of the Study:
- To extensively measure steady shear viscosity, longitudinal elastic modulus, and ultrasonic absorption of C12E8 aqueous solutions.
- To elucidate the structural properties and viscoelastic behavior across different concentration regimes.
- To investigate the influence of temperature and concentration on these properties.
Main Methods:
- Measurements of steady shear viscosity (eta degrees(s)).
- Measurements of longitudinal elastic modulus (M').
- Ultrasonic absorption (alpha) measurements across a range of frequencies and temperatures.
Main Results:
- Two distinct concentration intervals with different structural properties were identified.
- Surfactant-rich regions exhibited glass-like viscosity and universal viscoelastic behavior.
- Water-rich regions showed complex aggregate formation with multiple relaxation rates.
Conclusions:
- C12E8 solutions display concentration-dependent structural transitions affecting viscoelasticity.
- The surfactant-rich phase exhibits behavior analogous to glass-like systems.
- The water-rich phase involves dispersed aggregates with dynamics influenced by water and surfactant exchange.
More Related Videos
Related Concept Videos
01:18Newtonian Fluid: Problem Solving
Newtonian fluids exhibit a constant viscosity, meaning their shear stress and shear strain rate are directly proportional. This property ensures a predictable and stable response to applied forces, maintaining a linear relationship between force and flow. Examples include water, air, and light oils, consistently demonstrating this proportional behavior regardless of external conditions.
A velocity gradient forms within the fluid when a Newtonian fluid is placed between two parallel plates, with...
A velocity gradient forms within the fluid when a Newtonian fluid is placed between two parallel plates, with...
01:27Types of Fluids
Fluids can be classified into Newtonian and non-Newtonian fluids based on their response to shear stress. Newtonian fluids have a linear relationship between shear stress and the shear strain rate, following Newton's law of viscosity. Their viscosity remains constant regardless of the shear rate, making their behavior predictable and easier to analyze. Common examples include water, air, oil, and gasoline.
In contrast, non-Newtonian fluids do not follow Newton's law of viscosity, and their...
In contrast, non-Newtonian fluids do not follow Newton's law of viscosity, and their...
02:57Surface Tension, Capillary Action, and Viscosity
Surface Tension
The various IMFs between identical molecules of a substance are examples of cohesive forces. The molecules within a liquid are surrounded by other molecules and are attracted equally in all directions by the cohesive forces within the liquid. However, the molecules on the surface of a liquid are attracted only by about one-half as many molecules. Because of the unbalanced molecular attractions on the surface molecules, liquids contract to form a shape that minimizes the number...
The various IMFs between identical molecules of a substance are examples of cohesive forces. The molecules within a liquid are surrounded by other molecules and are attracted equally in all directions by the cohesive forces within the liquid. However, the molecules on the surface of a liquid are attracted only by about one-half as many molecules. Because of the unbalanced molecular attractions on the surface molecules, liquids contract to form a shape that minimizes the number...
01:19Viscosity of Fluid
Viscosity measures the resistance a fluid offers to flow and deformation. It results from internal friction between layers of fluid moving relative to one another. Dynamic viscosity, denoted by the Greek letter mu (μ), quantifies the force needed to move one fluid layer over another. For Newtonian fluids like water and air, the relationship between the shearing stress and the rate of shearing strain is linear, meaning their viscosity remains constant regardless of the applied stress.
01:17Viscosity
When water is poured into a glass, it falls freely and quickly, whereas if honey or maple syrup is poured over a pancake, it flows slowly and sticks to the surface of the container. This difference in the flow of different kinds of liquids arises due to the fluid friction between the liquid layers and the liquid and the surrounding material. This property of fluids is called fluid viscosity. In this example, water has a lower viscosity than honey and maple syrup.
The SI unit of viscosity is...
The SI unit of viscosity is...
01:27Viscosity
Viscosity is a property of fluids that measures their resistance to flow. It is influenced by factors such as the surface area of contact, the gradient of flow speed, and the fluid's viscosity constant, called the coefficient of viscosity. The coefficient of viscosity, also known as dynamic viscosity, is denoted by the symbol η. It determines the proportionality between the viscous force and the gradient of flow speed.Newton's law of viscosity states that the viscous force on a faster-moving...