What is rheokinetics
Rheokinetics, a contraction of the terms rheology and kinetics, sometimes referred to as chemorheology, is the science that studies the evolution of the rheological behavior of a system during the chemical reaction.
Rheology and rheokinetics, what are the differences?
If it is related to rheology, rheokinetics is a separate discipline with specific needs.
In practice, rheology makes it possible to determine the macroscopic mechanical properties from a study based on the micro or nanoscopic structure of the material, such as the molecular size and the architecture of a polymer in solution or the size distribution. of particles in a solid suspension.
Rheology consists in following the evolution of the viscosity of non-reactive products as a function of deformation, frequency or temperature. To do this, the most commonly used geometries are continuous rotation and oscillatory rotation which, through simple calculations, transform the values of torque and strain into viscosity.
However, this has disadvantages geometry upon reaching excessively high viscosity values, as is the case during a crosslinking reaction of an epoxy resin for example.
Thus, rheological analysis tools are unsuitable for analyzing the transition of reactive products from the liquid state to the viscoelastic solid state. Either they provide a single value (or only the start of the reaction) in the case of measurements in continuous rotation, or they provide an almost complete curve but at the cost of constant modifications of the frequency or of the deformation.
Oscillatory translation (or linear oscillation) does not present the faults of the methods by rotation. Used for the study of blood clotting for almost a century, it was then transposed to the study of the coagulation of milk after the Second World War. In the 1970s, a standard allowing the gel time of polyester resins to be measured also uses this method with parameters adapted to this type of material.
The advantages of oscillatory translation are multiple:
a sollicitation at low frequency and low amplitude allowing not to disturb the current reaction;
a robust mechanical system to protect the instrument during hardening of the material;
a conservation of the test parameters from the start to the end of the reaction.
Oscillatory translation is the only dynamic mechanical analysis method allowing such performance.
Example of a curve obtained on an epoxy resin during a cup test (2mm thickness)
Example of a curve showing the rennet-induced coagulation of milk during a test in a beaker (100 ml) at 40 ° C.
Example of blood clottingduring a test in a hemolysis tube at 37 ° C.
Par le passé, des appareils dont le nom contenait le préfixe Trombo- étaient basés sur cette méthode. Nos appareils, bien que basés sur une mécanique et des électroniques différentes, sont bien évidement entièrement compatibles avec ceux-ci.
Si vous possédez un équipement de type Trombomat, Trombolab ou Trombotech, contactez-nous pour discuter ensemble des bénéfices de nos solutions.