The last post described some of the potential pitfalls of the controlled stress measurements.  Controlled stress measurements are good if you require a precise yield point measurement.  An example would be if you were designing the yield point for a particular dispensing application.  The point-to-point creep test would allow the yield point to be measured accurately.  If on ... [Click to Continue...]

The last post described the controlled stress experiment.  In the image above, a stress was applied to the sample and the deformation as a function of time (strain-rate) was measured at steady state.  There are two measurement modes for controlled stress curves: Manual: a series of creep measurements (which was used above) Automatic: Flow or viscometry mode in a ... [Click to Continue...]

This post will cover the interpretation of a typical controlled stress flow curve for a highly filled uncured material.  In many electronic applications, the adhesive or coating is applied to the substrate using dispensing equipment where the filled material is in a syringe and either air pressure or an auger is used to flow the material through a small needle onto the ... [Click to Continue...]

Rheometers are used to determine the viscosity by measuring the stress at a known shear-rate or measuring the shear rate at a known stress.  There are two types of torsional rheometers: Controlled strain (most common) Controlled stress In the case of the strain controlled rotational rheometer, a typical configuration is shown in the following figure: In this ... [Click to Continue...]