Natural cork and its agglomerates as substitutes for high-density expanded polystyrene foams in sandwich cores

Abstract

Abstract Natural cork (NC) and its agglomerates are renewable materials that could be effective substitutes for non-renewable foams, such as expanded polystyrene (EPS), in the cores of sandwich materials. Although many existing studies have analysed the behaviour of different cork agglomerates under tensile, compression, or shear loads, no studies to date have simultaneously analysed the behaviour of multiple cork materials under all these loads. Therefore, in this study, the behaviour of NC and five cork agglomerates were analysed under tensile, compression and shear loads, and the mechanical and specific properties and the shape of the stress–strain curves were compared with those obtained for five EPS counterparts to analyse the relationship between the mechanical behaviour of the core and the main failure modes of the sandwich. Although EPS exhibited higher specific properties, NC exhibited higher mechanical properties under all the loads. The agglomerates all exhibited lower mechanical properties except for shear strain. Additionally, because no specific standards were available for testing cork products, slightly modified standards for testing other materials were adopted.