Dynamic oscillatory testing has become a common way of characterizing polymeric materials over the last few decades. Dynamic frequency sweep testing on polymer melts provides useful information on the molecular weight and molecular weight distribution and some branching information on thermoplastic materials. This testing has become, essentially, a quality control test for some materials.<br/>Dynamic oscillatory testing, generally at 1 frequency, is also useful for monitoring the curing behavior of thermosetting materials. With these materials, it is common to look for a gel point, often the point of the storage modulus (G’) – loss modulus (G”) crossover, that allows one to gauge the kinetics of the crosslinking reaction.<br/>In this presentation, we discuss a seldom-used experimental technique – multi-wave testing. Performing this testing on polymer melts provides one with frequency sweep data in a fraction of the time that conventional frequency sweeps require. Multi-wave testing also enables one to determine an unambiguous, true gel point for curing materials, specifically, the point where tan delta has the same value for all frequencies. This is especially useful with materials that do not have a clear G’-G” crossover, but this method is useful even when there is a crossover point.

Multi-wave oscillation testing on rotational rheometers to expedite testing and characterize the true gel point of curing caterials

ACS Spring 2022

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.