Dynamic mechanical analysis of fish dermal armour from A. gigas and P. pardalis

Fish scales and fish dermal plates are collagen-based structures with interesting mechanical properties especially as model materials for bioinspired nanocomposites. This paper reports the dynamic mechanical behaviour of two types of fish body armour structures: fish scales from Arapaima gigas and dermal plates from Pterygoplichthys pardalis. Both structures were tested using a dynamic mechanical analyzer (DMA) to determine their storage modulus and their loss factor as a function of temperature. DMA provides information on the damping properties and energy dissipation characteristics of these types of dermal armours. Although both materials are made out of collagen reinforced with hydroxyapatite, fish scales display a laminated structure, while dermal plates show a sandwich-like porous structure. Arapaima gigas scales showed a transition at around 0–10 °C, while P. pardalis dermal plates displayed behaviour similar to bone with no definitive thermal transitions. Fish scales showed a higher capacity for energy dissipation during deformation, quantified by a higher value of the loss factor, compared to dermal plates and likely due to their fibre reinforced laminated structure.