Bioresin infused then cured mycelium-based sandwich-structure biocomposites: Resin transfer molding (RTM) process, flexural properties, and simulation

A new approach to manufacture biocomposite sandwich structure is introduced with all materials naturally derived, including jute, flax and cellulose textile as reinforcement skin; mycelium-bound agricultural waste as lightweight cores; and a soy-based bioresin as a matrix. This new material could be used to replace many of the plastic products that are widely used today and therefore preventing the production of waste, while increasing efficiencies in the use of nonrenewable resources. This paper focuses on the final step of the seven-step manufacturing process: resin infusion followed by curing in place for the grown then deactivated mycelium sandwich beams. Specific process details that are highlighted include designing and building the preliminary transparent resin transfer molding for resin flow behavior study, design and fabrication of the aluminum permanent mold prototype, three-point bending flexural tests of the resin infused then cured sandwich beams to determine their strengths, and finally, finite element simulation using Abaqus software to simulate the three-point bending process. To obtain the skin reinforcements' Young's and shear moduli, tensile and V-groove shear tests were performed based on corresponding ASTM standards. It is concluded that although the skin material is the one that carries most of the loads, the strength of the sandwich structure appears to largely depend on the degree of fungal colonization within the core and bonding between the skin and core. The cured resin increased the beams' core shear ultimate stress, core shear yield stress, skin ultimate stress and flexural strengths of the sandwich beams by factors of 1.5-6.5, and the finite element simulation results agreed with the actual situations, which well explained the beams' most common failure mode in flexural bending.