title: Siliceous spicules enhance fracture-resistance and stiffness of pre-colonial Amazonian ceramics.
abstract: Pottery was a traditional art and technology form in pre-colonial Amazonian civilizations, widely used for cultural expression objects, utensils and as cooking vessels. Abundance and workability of clay made it an excellent choice. However, inferior mechanical properties constrained their functionality and durability. The inclusion of reinforcement particles is a possible route to improve its resistance to mechanical and thermal damage. The Amazonian civilizations incorporated freshwater tree sponge spicules (cauixí) into the clay presumably to prevent shrinkage and crack propagation during drying, firing and cooking. Here we show that isolated siliceous spicules are almost defect-free glass fibres with exceptional mechanical stability. After firing, the spicule Young's modulus increases (from 28 ± 5 GPa to 46 ± 8 GPa) inferring a toughness increment. Laboratory-fabricated ceramic models containing different inclusions (sand, glass-fibres, sponge spicules) show that mutually-oriented siliceous spicule inclusions prevent shrinkage and crack propagation leading to high stiffness clays (E = 836 ± 3 MPa). Pre-colonial amazonian potters were the first civilization known to employ biological materials to generate composite materials with enhanced fracture resistance and high stiffness in the history of mankind.
authors: Institut für Anorganische Chemie und Analytische Chemie, Johannes Gutenberg-Universität Duesbergweg 10-14, 55099 Mainz, Germany.|Institut für Chemie, Martin Luther Universität Halle-Wittenberg, Kurt-Mothes Str. 2, 06120 Halle (Saale) Germany.
authors: Filipe
authors: F
authors: Natalio
authors: Max Planck Institut für Polymerforschung, Ackermannweg 10, 55128 Mainz, Germany.|Instituto de Alta Investigación, Universidad de Tarapacá, Casilla 7-D Arica, Chile.
authors: Tomas P
authors: TP
authors: Corrales
authors: Max Planck Institut für Polymerforschung, Ackermannweg 10, 55128 Mainz, Germany.
authors: Stephanie
authors: S
authors: Wanka
authors: Julius Wolff Institut, Charité- Universitätsmedizin Berlin, Augustenburger Platz 1, 13353 Berlin, Germany.
authors: Paul
authors: P
authors: Zaslansky
authors: Max Planck Institut für Polymerforschung, Ackermannweg 10, 55128 Mainz, Germany.
authors: Michael
authors: M
authors: Kappl
authors: Museu Paraense Emílio Goeldi (MPEG), Av. Perimetral 1901, Terra Firme, 66070-530, Belém, Brasil.
authors: Helena Pinto
authors: HP
authors: Lima
authors: Max Planck Institut für Polymerforschung, Ackermannweg 10, 55128 Mainz, Germany.
authors: Hans-Jürgen
authors: HJ
authors: Butt
authors: Institut für Anorganische Chemie und Analytische Chemie, Johannes Gutenberg-Universität Duesbergweg 10-14, 55099 Mainz, Germany.
authors: Wolfgang
authors: W
authors: Tremel