Development of Epoxy and Urethane Thermosetting Resin Using Chlorella sp. as Curing Agent for Materials with Low Environmental Impact

In the current system, the disposal of plastic materials causes serious environmental pollution such as the generation of carbon dioxide and destruction of the ecosystem by micro-plastics. To solve this problem, bioplastics, biomass and biodegradable plastics have been developed. As part of our research, we have developed novel bioplastics called "cell-plastics", in which a unicellular green algal cell serves as a fundamental resource. The production of the cell-plastics would be expected to reduce environmental impact due to the usage of a natural product. Herein, to overcome the mechanical strength of cell-plastics, we used thermosetting epoxy and urethane resins containing Chlorella sp. as the green algae. We successfully fabricated thermosetting resins with a Chlorella sp. content of approximately 70 wt% or more. IR measurements revealed that the chemical structure of an epoxide or isocyanate monomer mixed with Chlorella sp. was modified, which suggests that the resins were hardened by the chemical reaction. In addition, we investigated the effect of thermosetting conditions such as temperature and compression for curing both resins. It was revealed that the Young's moduli and tensile strengths were controlled by thermosetting temperature and compression, whereas the elongation ratios of the resins were constant at low values regardless of the conditions.