Conference Dates

October 4-9, 2015


Living organisms are known to form a large variety of mineral-organic composite structures with mechanical properties that combine high stiffness, strength, toughness and perform at different levels of relative humidity (RH). Usually, the organic components are spatially limited to sub-micrometer features and are confined by a much stiffer mineral material. Mechanical characterization of these organic features, whose properties are strongly influenced by RH, presents a real technical challenge. In the present work we demonstrate our ability to measure environmentally dependent static and dynamic mechanical performance of 1 µm thick organic films in the prismatic layer of the mollusc shell Pinna nobilis employing the nanoscale modulus mapping technique. Two recent developments were utilized during the mechanical characterization process: (1) Environmental control during measurements enabled us to perform the modulus mapping in RH ranging from 0 to 98% [1]; (2) The concept of effective mass of the nanoindenter tip/sample configuration enabled us to account for drastic changes in elastic properties of the organic phase with increasing RH [2]. The possibilities and the limitations of this methodology with regards to structural and mechanical properties of the studied prismatic microstructure in the shell will be discussed.