MEASUREMENT OF THE EXTENSIONAL VISCOSITY OF M1 IN A CONVERGING CHANNEL RHEOMETER

Measurements of the extensional viscosity of M1 were made in a converging channel rheometer. The high viscosity of the fluid made it necessary to operate the instrument at Reynolds numbers lower than it was designed for, but analysis of the stress field showed that the normal stress difference in extension could still be detected from the measurement of pressure drop. Measurements of ηE were made at rates of extension up to 190 s-1, for temperatures from 21 to 40 ° C, and at three locations along the channel, i.e. for increasing strain. The data show that ηE depends strongly on strain and increases approximately linearly with the rate of extension ∈ .. © 1990.