In the last post we discussed how changing the resin content and the prepreg degree of B-stage advancement impacted the flow during lamination and the viscosity profile during non-isothermal curing.  Another technique used to tailor the flow during processing is to vary the curing kinetics.  Typical thermosets have a reactive resin and a hardener (crosslinking agent).  Some ... [Click to Continue...]

The prepreg resin content and degree of B-stage advancement (percent conversion) were shown to have an impact on the flow during lamination.  As presented in the previous post, the figure on the left shows the flow number for several specially prepared prepregs.   To validate that the flow number obtained using the squeezing flow was close to the flow number measured ... [Click to Continue...]

This post will focus on examining the lamination performance of the three types of prepregs described in the previous post.  Three prepreg samples were made using a production treater tower. The  table in the figure on the left summarizes the resin content and degree of B-stage advancement (percent conversion). The figure also demonstrates how the B-stage advancement controls ... [Click to Continue...]

In this post we will briefly review the viscosity changes during the non-isothermal heating of B-staged epoxy prepregs and describe a set of carefully controlled prepreg samples used to demonstrate the utility of the squeezing flow test.  Recall that during non-isothermal processing, at the B-staged prepreg glass transition temperature (Tg), the resin viscosity decreases ... [Click to Continue...]

In the last post we introduced the concept of the squeezing flow test and how the viscosity is related to the rate of platen closure using the Stefan equation.  We also described a custom fixture (shown at left) developed at Syracuse University jointly with IBM to investigate the rheological properties during squeezing flow testing.  In the next few posts we will be showing ... [Click to Continue...]