Chapters 3 and 4 presented chemical, physical and chemorheological techniques useful for characterizing various reactive polymer systems. This chapter will now focus on a review of chemorheological analyses for a variety of polymer systems, including detailed experimental findings and chemorheological modeling.
Chemoviscosity and chemorheological models
Chemorheology is defined as the study of the viscoelastic behaviour of reacting polymer systems. This involves examining the effects on chemoviscosity of chemical reactions (cure conversion, cure kinetics) and processing conditions (temperatures, shear rates), as well as gelation and vitrification. In Chapter 4 we briefly summarized chemoviscosity models that highlight effects of cure (ηc=ηc(Τ, α)), shear rate (ηsr=ηsr(γ, Τ)) and filler (ηf=ηf(F, Τ, t)) in Tables 4.4–4.6. This chapter will examine the development of chemorheology and chemorheological modelling in more detail by examining the chemorheology and chemoviscosity models of unfilled reactive systems, overviewing the effects of fillers on chemoviscosity and then presenting chemoviscosity data and models for filled systems. It is hoped that, by presenting the data and models in more depth, a better understanding of the chemorheology of systems will be obtained.
Chemorheological models for neat (unfilled) curing systems can be grouped into the following categories:
simple empirical models
structural and free-volume models
probability-based and molecular models
Simple empirical models
Malkin and Kulichikin (1991) initially reviewed the rheokinetics of cured polymers and highlighted the first empirical chemorheological models.