Dehnviskosität von Kautschukmischungen

It is shown that the extensional viscosity measured by uniaxial stretch may give useful information as to the processability of rubber compounds. A simple apparatus was constructed to measure this rheological property at constant rate of strain. The influence of rubber type, filler, aging, mastication and degree of crosslinking on the reduced stress is represented by diagrams. No steady-state extensional viscosity was obtained for highly filled rubber compounds. It was found that the flow behaviour of rubber compounds can be better characterized with an extensional rheometer than with a high-pressure capillary rheometer.