The purpose of this research project is to model the rheological
behaviour of elastomers and elastomer compounds. Two elastomers
(natural rubber, SMR 20 and chlorosulphonated polyethylene, Hypalon
40) and three different grades of carbon black at three different
levels of loading were chosen for this study. Mixing was carried out
with a Farrel Bridge BR Banbury mixer, followed by subsequent milling
on a two-roll mill. Rheological measurements were made with parallel
plate, cone and plate and Negretti biconical rotor TMS rheometers .
. The effect of temperature on viscosity was investigated by determining
the activation energy of viscous flow in terms of concentration and
surface area of carbon black.
Computer programs were developed to evaluate various parameters in the
models by non-linear optimisation technique. The steady state flow
behaviour of gum elastomers was fitted by the Bird-Carreau model and a
thixotropic model. The thixotropic model was modified to non-
Newtonian flow but proved to be intractable for fitting the
rheological properties of mixed rubber compounds. Two new models for
the viscosity and stress relaxation of filled compounds were then
developed, which give very promising results.
A Doctoral Thesis. Submitted in partial fulfilment of the requirements for the award of Doctor of Philosophy of Loughborough University.