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
Oscillatory translation (or linear oscillation) does not have the drawbacks of rotational methods . Used for the study of blood coagulation for almost a century, it was applied after the Second World War to the study of milk coagulation.
In the 1970s, the ISO 2535 standard, "Measurement of freeze time at room temperature," adopted this method with parameters adapted to polyester resins. In the 1980s and 90s, devices such as the Trombomat, the Trombolab, and more recently the Trombotech, were marketed.
The advantages of oscillatory translation are numerous:
complete reaction curve;
global approach: physical AND thermal behavior;
low frequency and low amplitude stress so as not to disturb the ongoing reaction ( low shear );
robust mechanical system to protect the device during the hardening of the material;
conservation of test parameters from the beginning to the end of the reaction ( less expensive electronics ).
Oscillatory translation is the only dynamic mechanical method that allows 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.
If you own Trombomat, Trombolab or Trombotech type equipment, contact us to discuss the benefits of our solutions.