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...]

In our last post we discussed the various experimental details for a dynamic mechanical analysis. This post will cover the application of DMA to investigate the glass transition temperature (Tg) as well as measure the dynamic moduli as a function of temperature.  DMA is particularly useful for characterizing thermosets since information on both the Tg and mechanical properties ... [Click to Continue...]

In the last post an introduction to DMA was presented to set the stage for the next two posts.  In this post I will discuss the various types of geometries that can be used in DMA experiments as well as some guidelines for instrument parameters.  First let’s discuss sample geometries. Single Cantilever Beam Unsupported samples can be made in Teflon or silicone rubber ... [Click to Continue...]