You did link to a material containing cells. One thing to consider is if you are interested in measuring the properties of a raw material or the properties of a product, where the material may no longer be homogenous, or where there may be a difference between micro and macro scale.

An example - you may decide to measure thermal conductivity in polystyrene. But you may just as well see a big interest in measuring the thermal conductivity of styrofoam, since a lot of users of styrofoam are interested in how well it isolates their houses. The manufacturer would be very much interested in the possibility to change the size of the bubbles, and measure how the bubble sizes affects the thermal conductivity.