A Novel Tensile Specimen Configuration for the Characterization of Bulk Mycelium Biopolymer

Mycelium is a biopolymer that has the potential to be a sustainable replacement for petroleum based foams in some engineering applications. During a recent study, with the objectives to first relate the effects of growing conditions on material properties and second to develop a model to predict the bulk behavior of mycelium, it was found that a variety of standard test methods are being used for the tensile characterization of mycelium in the literature. In the current study, these test methods were found to cause stress concentrations that resulted in maximum loads away from the gauge section, griping conditions that crushed the test samples through the thickness, and gauge sections that were smaller than the level of heterogeneity typically observed in samples of mycelium biopolymer. A new tensile specimen configuration has been developed that mitigates the issues associated with other specimen configurations. This new specimen configuration is used to determine the tensile strength, tensile modulus, and Poisson's ratio of mycelium biopolymer specimens.