| Abstract: | The dynamic shear properties of a natural rubber and several commercial synthetic polyisoprenes were measured in a Rheometrics mechanical spectrometer. The dynamic viscosity vs angular velocity curve was fitted to the three-constant Car, reau model. The rheological parameters were correlated with molecular characteristics such as gel content and weight average molecular weight. The viscosity measurements at high shear rate were obtained from capillary rheometry. The viscosity vs shear rate curve at the low shear rate end was found to be superimposible on the plot of dynamic shear viscosity vs twice the angular velocity. |
