Thermoset rheological characterization is typically done using controlled strain experiments.  We discussed this in the Dynamic Mechanical posts in the characterization series.  For rheometry, we use a rotational shear geometry so we are reporting the dynamic loss modulus as G” and the dynamic storage modulus as G’.  As discussed in the previous post, the most common geometry ... [Click to Continue...]

This post will cover the types of rheological measurements available for characterizing thermosets.  Rheology is important in two aspects of thermoset processing.  The first is during the application or dispensing of the uncured thermoset (for example an highly filled adhesive or coating) and the second is characterizing the viscosity changes during the curing process.  In the ... [Click to Continue...]

First a few background concepts to get us started.  Rheology is the science of deformation and flow of matter under controlled testing conditions.  Rheological testing is a powerful way to probe the structure-property-processing relationships in many types of polymers.  The viscosity-shear rate profile is important in the processing of thermoplastics (like injection molding and ... [Click to Continue...]

In the  next couple months we will be providing a “deep dive” into the field of rheology and specifically how rheology is a key tool in the characterization of thermosets.  But first a little background.  I am a classically trained rheologist having completed my Ph.D. at Northwestern University under the guidance of Prof. William W. Graessley.  To those in the field, Prof. ... [Click to Continue...]

In this post we will present some additional examples of how DMA can be a useful tool for thermoset characterization.     In the following figure, a partially cured fiberglass reinforced prepreg was analyzed.  A prepreg is typically a woven fiberglass fabric that is impregnated with a thermoset resin and partially cured.  Since the material will soften during ... [Click to Continue...]