Bio-based leather alternatives: an evaluation of elastic properties

Abstract As a result of increasing sustainability efforts in the field of material research, various approaches have been developed to replace leather with bio-based alternatives. Approaches based on fungi, nanocellulose, and cellulose fibers have been investigated in the literature, with a focus on their fundamental physical properties, revealing considerable variability. However, the relationship between elongation and elasticity has not been considered, even though it is of great importance for applications in the upholstery industry, as the material’s ability to recover its original shape after mechanical deformation is critical. Due to this, it remains unclear in terms of which of the various bio-based alternatives closely mimics the properties of leather. Therefore, several bio-based leather alternatives were investigated to obtain a comprehensive evaluation of elastic properties. The evaluation of elasticity is based on a tripartite analytical framework: tensile elasticity for multiple elongation limits, reduction of elasticity under multicyclic loads, and creep resistance. A prior analysis of the composition and structure enabled a comparative assessment within and across the defined material categories, which were based on three approaches: naturally grown materials, coated textiles and non-woven plant fibers. The results show that, although the investigated bio-based leather alternatives exhibited varying properties, their performance is strongly influenced by the underlying material approach. None of the investigated materials were able to fully replicate all examined elastic properties of genuine leather, even when high concentrations of synthetic polymers such as polyurethane were incorporated. At this stage of material development, the use of the investigated leather alternatives in the upholstery industry cannot be recommended, as either the elongation is insufficient, or their elastic properties are not comprehensive enough compared to leather or synthetic leather.