Characterization of Arapaima Fish Scales and Related Reinforced Epoxy Matrix Composites by XRD, EDS, and SEM

Abstract

Arapaima gigas, also known as pirarucu in Brazil, is one of the biggest freshwater fishes. The structure of the Arapaima scales is a composite consisting of a mineralized outer layer with surface corrugations and a flexible internal collagenous foundation and can be used as an inspiration for developing flexible composites as an intermediate layer in multilayered armor system. In this paper, the structure of the Arapaima scales was reviewed and structural, chemical, and morphological properties of the reinforced composites with 30% vol. of Arapaima scales. The SEM analysis of the morphology of the scales confirmed a sandwich structure, composed of an internal porous matrix surrounded by two external dense layers. Chemical analysis by XRD revealed that the scales’ outer surface contains calcium-deficient hydroxyapatite. The EDS results confirm that the percentage of calcium is higher in the outer layer. The experimental results provide an initial view of the potential use of Arapaima scales in epoxy composites.