Vol.:(0123456789) 1 3 Journal of Bio- and Tribo-Corrosion (2020) 6:35 https://doi.org/10.1007/s40735-020-0333-6 Physical and Morphological Properties of Snail (Achatina Fulica) Shells for Benefciation into Biocomposite Materials O. J. Gbadeyan 1  · G. Bright 1  · B. Sithole 2,3  · S. Adali 1 Received: 12 November 2019 / Revised: 16 January 2020 / Accepted: 5 February 2020 / Published online: 12 February 2020 © Springer Nature Switzerland AG 2020 Abstract In this study, microhardness and fow strength (tensile) of a shell of an African Giant snail (Achatina Fulica) were studied as a function of indentation load. The infuence of loading direction on the hardness of the nacreous and prismatic structure of the shell material was analyzed. The results revealed that microhardness measured on the shell was dependent on the load on the nacreous and prismatic structures. Indentation loading between 50 and 500 kN induced tensile strengths that ranged between 675–1050 and 390–810 MPa on the prismatic and nacreous layers, respectively. In addition, the morphology of the shell surface exhibited an interlocking structure with a large surface for binding to the organic matrix. The observed reinforcement of the shell explained the hardness property of the shell. The improved hardness of the shell implies that it can be benefciated into fller that may be used to improve the mechanical properties of polymeric composite materials. Keywords Snail shell · Microhardness · Tensile strength · Indentation loading · Microstructure 1 Introduction Snail shells are a ubiquitous waste in the environment. Many of them are generated after the processing and consumption of snails, e.g., by snail merchants, food, and cosmetics indus- tries [1]. Accumulation of waste shells in the environment constitutes a serious threat to human health and sometimes causes blockage of waterways [2, 3]. A study by Arias and Fernández [4] on shells, bone, and teeth classifed them as ceramic biocomposites consisting of layered assemblies of microscopic amounts of macromolecules with well-ordered inorganic structures rich in calcium that provides a material with unique morphologies and properties. Microstructural features such as organized, layered organic/inorganic assem- blies and the existence of spongy and fbrous elements in many biological components have become an inspiration for the development of biocomposite materials. Furthermore, the existence of organic and inorganic structural networks at molecular and micro-levels often form synergistic efects that signifcantly improve the mechanical properties of advanced nano-laminates and other composite materials made from them [5, 6]. Several studies have dem- onstrated the addition of these biological materials, in micro- particle size form, to polymeric materials and this resulted in improved composite materials. Also, a combination of two or more of these naturally sourced materials has been developed to produce advance materials with desired proper- ties [7–9]. However, there is a dearth of information on the fundamental properties of the materials that can be exploited for the manufacture of biocomposites. This may be due to the size of the biological materials—shells, in particular, do not have adequate size/space required to produce a standard specimen for measurement of mechanical properties. Despite this, valuable information on mechanical responses of the shell, such as tensile, may be obtained by conducting nano and micro-indentation (Vickers hard- ness test) studies on shell samples. Material hardness may not always be a fundamental property of a material; how- ever, mechanical properties such as yield strength, work hardening, and true tensile strength of a material may be * O. J. Gbadeyan toyin2good@gmail.com 1 School of Engineering, Discipline of Mechanical Engineering, University of Kwazulu-Natal, Durban, South Africa 2 School of Engineering, Discipline of Chemical Engineering, University of Kwazulu-Natal, Durban, South Africa 3 Biorefnery Industry Development Facility, Council for Scientifc and Industrial Research, Durban, South Africa