Fig 3. Influence of PAAm thickness on Young’s modulus.

A thin (a) as well as a 1 mm (b) and a 2 mm (c) thick PAAm sample indented with a bead of 21.82 μm diameter. Although indentation depths up to 10 μm were reached for the bulk PAAm samples, no plateau region was detected. Only the thin sample shows a plateau value for the Young’s modulus for indentation depths above 0.4 μm. Generally, Young’s moduli decrease with increasing sample thickness.