Epoxy Composites Based on Low-cost Carbon Filler Derived from Hydrothermal Carbonization of Waste

Different kinds of composites based on polymer matrix are present on the market. In particular, composites based on epoxy resin are used as high-performance polymers due to their excellent mechanical properties, chemical resistance, thermal stability and low cost production. Recently, in composites production the attention has been focused on the study of materials derived from biomass and organic waste to be used as filler.Hydrochar is a carbonaceous material obtained from hydrothermal carbonization (HTC) of biomasses and organic waste. During HTC biomass is carbonized in an aqueous environment at temperatures of 180-250?°C under saturated pressure (autogenous or provided by a gas) for several hours. For its characteristics, hydrochar can be potentially used as filler in composite materials in view of the growing concern about environmental sustainability.In this work, hydrochar obtained from hydrothermal carbonization of green waste was used as filler for the preparation of diglycidyl ether of bisphenol A-type epoxy composite materials. Two different epoxy matrices were used; the content of hydrochar was varied between 5 and 15 wt%. The resulting samples were characterized by morphologic and mechanical analyses, and electrical properties were evaluated. The addition of hydrochar to epoxy resins resulted in a slight increase of the elastic modulus, although there was a decrease in tensile strength and toughness. Moreover, electrical properties of epoxy resins were not significantly modified by the addition of hydrochar. Therefore, the study provided encouraging results for the production of innovative hydrochar-based epoxy composites, allowing the recycling and re-use of industrial waste.