Extensibility is beyond the paradigm of classical soft glassy materials, and
more broadly, yield-stress fluids. Recently, model yield-stress fluids with
significant extensibility have been designed by adding polymeric phases to
classically viscoplastic dispersions [1, 2, 3]. However, fundamental questions
remain about the design of and coupling between the shear and extensional
rheology of such systems. In this work, we propose a model material, a mixture
of soft glassy microgels and solutions of high molecular weight linear
polymers. We establish systematic criteria for the design and thorough
rheological characterization of such systems, both in shear and in extension.
Using our material, we show that it is possible to dramatically change the
behavior in extension with minimal change in the shear yield stress and elastic
modulus, thus enabling applications that exploit orthogonal modulation of shear
and extensional material properties.Comment: 23 pages, 13 figures, Supplementary Information included (6 pages