The KSV NIMA Interfacial Shear Rheometer provides an extremely sensitive method for measuring the viscoelastic properties of films at fluid interfaces (gas/liquid and liquid/liquid). Viscoelastic properties and surface pressure can be measured simultaneously. The film packing density can also be controlled while measuring.
Interfacial Shear Rheometer
- The most sensitive interfacial rheometer available—it is able to measure very weak elastic and viscous moduli of surfaces and interfaces. The high sensitivity of the method is due to fact that the low inertia hydrophobic probe is moved by magnetic field without mechanical connections. The high sensitivity is crucial in many applications, for example with experiments on fatty acids.
- In many applications, such as with biofilms, the long-lasting chemical interactions and film creation kinetics need to be followed in real-time. KSV NIMA ISR is the most suitable instrument for the long-lasting experiments as the probe is floating at the interface, and therefore its location does not demand any adjustments to compensate the influence of evaporation.
- The only interfacial rheometer to enable simultaneous measuring and controlling of surface pressure due to easy integration with KSV NIMA Langmuir Troughs. This makes it possible to correlate rheological data with monolayer surface pressure and phase transitions that are crucial when working with insoluble surfactants.
- Possibility to work with low volumes down to 4.7 mL saves time and cost when working with valuable compounds and subphases.
- Built-in data plotting option with capability of viewing multiple measurement results in one graph. Measured data can easily be exported and converted to a data file that is readable using common plotting software.
Emulsion and foam stability, bubble and micelle formation, breakage and fusion and interfacial reactions are largely affected by the rheological properties of the interface. Applications can be found in many industries. For example proteins, polymers, pigments, fluoroalkanes and other emulsifiers are strong stabilizers in dispersions and used in the pharmaceutical, cosmetic and food industries.
- Prediction of emulsion, froth and foam stability. Viscoelasticity of an interface can predict the stability of a complex fluid. Micelle/droplet fusion and fission are largely dependent on the interface viscoelasticity.
- Determination of thin film structure. The presence of networking, hydrogen bonding and other interactions can be detected from the viscoelastic behavior of films.
- Examination of phase transitions. Phase transitions in a monolayer (thin film) can result in a change in the rheological properties of the layer.
- Real-time monitoring of surface reactions. Surface gelation, network formation and protein denaturation at interfaces are detected from the changes in the viscoelastic properties at the interface.
- Continuous monitoring of molecule adsorption into interfaces. In many biological systems the adsorption and desorption at interfaces and surfaces can change viscoelasticity. Processes in cells such as mitosis are highly dependent on membrane rheology.
The KSV NIMA ISR method is based on interfacial shear rheology. A magnetized probe positioned at the interface is used to create shear deformation on the interface which response can be measured by recording the probe movement optically.
For more information about the technology, see:
- Interfacial Shear Rheometry
KSV NIMA ISR enables both dynamic and static measurements to define viscoelasticity of the interfacial layers. With dynamic measurement, viscoelastic properties are measured as a function of frequency, time, strain, temperature or surface pressure. Static measurement enables the creep test to be performed and indicates whether the system behaves like an ideal Newtonian liquid (dashpot model) or ideal elastic (spring model). These measurements enable the following parameters to be defined:
- Elastic (storage) modulus, G’
- Viscous (loss) modulus, G’’
- Dynamic interfacial viscosity, μs*
- Surface/interfacial viscosity, η
- Relaxation times, τ
The KSV NIMA ISR can be equipped with either a KSV NIMA Langmuir Trough (or Liquid-Liquid Trough) for simultaneous control of the film packing density or a Low Volume Measurement cell to work with small interfacial areas and reduced subphase volumes.
Both systems enable surface pressure measurement thanks to the integrated highly sensitive Wilhelmy balance. The Langmuir Trough and the Low Volume Measurement Cell are divided into an upper and lower compartment, which can be used to study film viscoelasticity at the liquid-air or liquid-liquid interface.
All the ISR systems have designed hardware solutions for easy injection of the chemicals to enable real-time chemical interactions studies.
KSV NIMA Interfacial Shear Rheometer with KSV NIMA Langmuir Trough
Combining the KSV NIMA ISR with a Langmuir Trough or Liquid-Liquid Trough enables the compression of both soluble and insoluble films to be controlled during the measurements. As with any KSV NIMA Langmuir Trough, measurements of Isotherms, Isobars and interfacial dilatational rheology are possible.
KSV NIMA Interfacial Shear Rheometer with Low Volume Measurement Cell
When working with valuable compounds and subphases, the KSV NIMA ISR can be used with the Low Volume Measurement Cell which requires as little as a 4.7 mL of subphase. It is ideal for studying material adsorption and reaction at interfaces. A quartz glass cover minimizes liquid evaporation and reduces the influence of airflows. An integrated water circulator enables temperature control from 10 to 60 °C. Two injection ports on each end of the Cell enable easy injection of materials (e.g. proteins, enzymes) in the subphase and allow gradual subphase exchange while measuring.
Interfacial Shear Rheometer
+ KSV NIMA Langmuir Trough
Interfacial Shear Rheometer
+ Low Volume Measurement Cell
Low Volume Measurement Cell
for KSV NIMA
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