A new manufacturing process for biocomposite sandwich parts using a myceliated core, natural reinforcement and infused bioresin

Abstract

Key aspects, process parameter effects and sensitivities and design models of the seven manufacturing steps were investigated and developed further. It was determined that the number of reinforcement plies should be maximized when cutting with steel rule dies to reduce the number of cutting defects. The resulting skin layups can be rapidly impregnated using a nip roller system with a starch-based glue that is continuously circulated, and an analytical model is available for designers to use. Forming, sterilizing and setting of the glue occur simultaneously using heated tooling coated with a ceramic-polymer composite where molding pressure and temperature play a key role. Integral tooling with preformed skins, although potentially offering significant manufacturing cost reductions, loses shape fidelity during the growth process in a high humidity environment. Conductive drying helps to bring the part back into shape conformance, although convective drying is still required to achieve the low moisture levels required by the industrial collaborator. Resin transfer molding with a soy-based bioresin is demonstrated to complete the process cycle. Finally, a manufacturing system model involving all seven steps is developed for system optimization purposes, and a case study to maximize profit is demonstrated.

A new approach to manufacture biocomposite sandwich structures from purely natural constituents and the corresponding analysis useful for process design are fully demonstrated in this thesis. The constituent materials include agricultural waste (agri-waste) bound together with fungal mycelium as core, natural textiles bound to the core surfaces with mycelium as reinforcement skins, and a bioresin, if needed, to stiffen and strengthen the skins for high performance applications. Based on a series of preliminary experiments, an optimized seven-step manufacturing approach is proposed including: (1) die cutting of skin reinforcement; (2) natural glue impregnation using a nip roller system to allow preforming of the skins; (3) forming/sterilizing of the preform skins with matched and heated molds to serve as integral tools; (4) filling the tools with agri-waste inoculated with mycelium vegetative tissue; (5) allowing the mycelium to grow and bind all constituents together; (6) convectively and conductively drying the workpiece to drive off water and inactive the mycelium; and (7) infusing skins with bioresin and allowing them to cure.