ISR Interfacial Shear Rheometer - Langmuir e Langmuir-Blodgett
Brand: KSV NIMA Product: ISR INTERFACIAL SHEAR RHEOMETER
The Interfacial Shear Rheometer is a unique instrument that provides an accurate and quantitative method to measure the shear properties of fluid interfaces (gas/liquid or liquid/liquid). The ISR can be combined with a KSV NIMA Langmuir trough, allowing measurements on both soluble and insoluble films. KSV NIMA produces, as well, a Low Volume Measurement Cell for its KSV NIMA Interfacial Shear Rheometer. It enables measurement of the shear properties of films with as little as a 4.7 ml subphase, enabling time and cost savings when working with valuable compounds and subphases.
The relationship between stresses and deformation defines the rheological properties of a film. Most systems encountered in industry and in biology are viscoelastic films where these relationships are nonlinear and intermediate between purely viscous and purely elastic responses. The rheological properties are extremely important for defining product stability in different industries such as food, petrochemical, cosmetics, and pharmaceuticals. For example protein layers and polymers are strong stabilizers in dispersion and typically used in the food industry for foams and emulsions. In the petrochemical industry oil extraction is performed in multiple steps where oil-water and water-oil emulsions are formed to recover oil and later on destabilized to separate the two phases. Many different kinds of emulsifiers, pigments and stabilizers are widely used in cosmetic and pharmaceutical industries such as lotions, creams and hair sprays.
- 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. - Continuous monitoring of molecule adsorption into interfaces - Especially in biological systems the adsorption and desorption at interfaces and surfaces can change viscoelasticity. Many processes in cells such as mitosis are highly dependent on membrane rheology.
The method marks a quantum leap in technology from the traditional rotational rheometers that lack the sensitivity to probe many of the phenomena occurring within a thickness range of a few nanometers. A magnetized probe, positioned at the air-liquid or liquid-liquid interface, is moved using a magnetic field. The movement of the probe is recorded with a digital camera from above. By measuring any changes in movement of the probe the surface modulus can be calculated and divided into the elastic and viscous properties of the film.