Mechanical characteristics of bacterial cellulose-reinforced mycelium composite materials

Lars De Laet,Elise Elsacker,Bastien Damsin,Eveline Peeters,Aurélie Van Wylick,Simon Vandelook

doi:10.1186/s40694-021-00125-4

Lars De Laet, Elise Elsacker + Show 4 more

Open Access

https://doi.org/10.1186/s40694-021-00125-4

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Abstract

BackgroundWhile mycelium is considered a promising alternative for fossil-based resins in lignocellulosic materials, the mechanical properties of mycelium composite materials remain suboptimal, among other reasons due to the weak internal bonds between the hyphae and the natural fibres. A solution could be provided by the hybridisation of mycelium materials with organic additives. More specifically, bacterial cellulose seems to be a promising additive that could result in reinforcing mycelium composites; however, this strategy is underreported in scientific literature.ResultsIn this study, we set out to investigate the mechanical properties of mycelium composites, produced with the white-rot fungus Trametes versicolor, and supplemented with bacterial cellulose as an organic additive. A methodological framework is developed for the facile production of bacterial cellulose and subsequent fabrication of mycelium composite particle boards based on a hybrid substrate consisting of bacterial cellulose and hemp in combination with a heat-pressing approach. We found that, upon adding bacterial cellulose, the internal bond of the composite particle boards significantly improved.ConclusionsThe addition of bacterial cellulose to mycelium composite materials not only results in a strengthening of internal bonding of mycelium material, but also renders tuneable mechanical properties to the material. As such, this study contributes to the ongoing development of fully biological hybrid materials with performant mechanical characteristics.

Highlights

While mycelium is considered a promising alternative for fossil-based resins in lignocellulosic materials, the mechanical properties of mycelium composite materials remain suboptimal, among other reasons due to the weak internal bonds between the hyphae and the natural fibres
This substrate, in which the bacterial cellulose (BC) nanofibrils have presumably self-assembled repetitive building blocks into higher-order structures to form a networklike tissue around the hemp fibres, was used to sustain growth of T. versicolor in a classical set-up for Bending behaviour of BC‐mycelium composites As a first step towards assessing the mechanical performance of BC-mycelium composite particle boards, all particle board samples were subjected to bending behaviour analysis using a three-point static flexural test (Table 1; Fig. 3)
Increasing the heat to 200 °C during the densification process even improved the flexural strength of the samples (BCmycelium_200°C) by 200% compared with the control sample, and by 150% compared with samples densified at 70 °C (BC-mycelium_70°C) (Table 1; Fig. 3)

Summary

Introduction

While mycelium is considered a promising alternative for fossil-based resins in lignocellulosic materials, the mechanical properties of mycelium composite materials remain suboptimal, among other reasons due to the weak internal bonds between the hyphae and the natural fibres. Lignocellulosic fibres are an appealing feedstock for such bio-based substitutes as they allow for the valorisation of Elsacker et al Fungal Biology and Biotechnology (2021) 8:18 a unified and lightweight composite material [2]. After substrate colonisation, this composite is heated to kill the fungal organism and remove the moisture [5]. Depending on the type of processing and raw material, the method is quite energy-intensive and requires chemicals for fibrillation pre-treatment [11, 24]

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