B. Frýdová

Mechanical properties of deep-sea molluscan shell

Mechanical properties of deep-sea molluscan shell I. Hrabankova, J. Frýda, J. Sepitka, T. Sasaki, B. Frýdova & J. Lukes a Faculty of Environmental Sciences, Czech University of Life Sciences, Kamýcka 129, Praha, Czech Republic b Czech Geological Survey, P.O.B. 85, 118 21, Prague 1, Czech Republic c Czech Technical University, Faculty of Mechanical Engineering, Biomechanics and Mechatronics, Prague, Czech Republic d The University Museum, The University of Tokyo, 7-3-1, Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan e VURV v.v.i., Crop Research Institute, Drnovska 507, 161 06, Prague – Ruzyne, Czech Republic Published online: 07 Aug 2013.

Crystallographic texture determines mechanical properties of molluscan nacre

1. IntroductionThe study of biologically controlled mineralisationrepresents an essential issue of modern science. Molluscannacre (mother-of-pearl) is one of the most studiednanocomposite materials. Nacre is found in the inner layerofsomeseashells,anditiscomposedof anaragonitephase(about 95vol.%) arranged in microscopic polygonal flattablets,bondedtogetherbyabiopolymerthinfilm(Figure1).Published data on the mechanical properties of molluscannacre show a rather high variability (Barthelat et al. 2007).The reasons for such a high variability are still a matter ofscientificdiscussion.Differenttexturalarrangementsofthearagonitic platelets are one of the possible parametersinfluencing the mechanical properties of the nacre. Twobasictexturaltypesofbivalvenacre(unorderedandorderednacre) have been documented, differing by their arrange-ments of the a- and b-axis of aragonite (Figure 1).Here, we use a combination of nanoindentation andelectronbackscatterdiffraction(EBSD)totestwhetherthecrystallographic texture of nacre controls its mechanicalproperties. The aims of this study are as follows: (1) todeterminate the hardness (H) and reduced elastic modulus(E