Improving wear resistance of epoxy resin using bio-oil from hemp biomass: A sound strategy to reduce environmental impact

Abstract

Efforts are underway to convert biomass into valuable bio-based chemicals, fostering reduced dependence on fossil fuels and advancing sustainability. In this work, various amounts of hemp bio-oil were used to partially replace the amine-based curing agent in a commercial epoxy resin designed for the building sector. All the so-formulated epoxy systems showed a complete degree of curing. The values of crosslinking density decreased to 30% at the highest bio-oil concentration and it was hypothesized that some components of bio-oil reacted with epoxy units acting as dangling groups to resin. These features significantly affected the mechanical properties of the bio-resins: by increasing the amount of bio-oil, the Martens hardness and the indentation Young's modulus decreased (by 20 and 37%, respectively when the bio-oil was half the amount of the amine-based curing agent), while the damping ability of the bio-resin increased. For the commercial resin, the wear track showed an average depth of 86 ± 15 μm and a specific wear rate of 3.62 × 10⁻⁴ mm³/N·m. These values decreased by 59 and 89%, respectively, when the bio-oil used was half the amount of the amine-based curing agent. The results of the life cycle assessment, including the hemp hurd separation from fibers in the system boundaries, appeared only slightly favorable for the bio-based solutions. However, when also considering the technical life (i.e., wear resistance) of the resins, a significant reduction of all impacts was observed, achieving more than 80% when bio-oil was half the amount of the amine-based curing agent.