Single fiber tensile strength of seagrasses and the development and characterization of Zostera marina-based medium density boards

• Posidonia oceanica fibers display a tensile strength of 123 MPa. • Seagrass leaves provide a sustainable alternative for MDF production. • Seagrass-based boards display high fire resistance and low thermal conductivity. • Seagrass-boards show promising potential for non-structural interior applications. This study investigates the potential of the leaves of the seagrass Zostera marina (ZM) as an alternative raw material for the production medium-density boards. In the first part, the tensile strength properties of various types of seagrasses were investigated. Posidonia oceanica fibers (POF) exhibited a mean tensile strength of up to 123 MPa, while its leaves (POL) reached up to 27 MPa. The ZM leaves also showed a similar tensile strength to Posidonia oceanica leaves, 22.9 MPa. In the second part, ZM leaves and wood fibers (WF) are further processed to produce medium density boards with densities ranging from 500 to 700 kg m −3 . The boards were evaluated for fire resistance, thermal conductivity, mechanical strength, and water resistance-related properties. ZM-boards demonstrated high fire resistance and lower thermal conductivity compared to boards based on wood fiber (WF), i.e. medium density fiberboards (MDF), of similar density. However, due to the low tensile strength and unique morphology of the seagrass leaves, ZM-boards display a lower flexural strength (up to 10.9 MPa) and lower resistance to water absorption compared to boards produced from wood fibers (WF). Boards made by Zostera marina can be a promising alternative to commercial MDF panels especially for interior applications prioritizing fire protection and thermal insulation but they are mainly suited for non-structural uses. Further examination of its acoustic properties would assess its potential applications as sound-absorbing architectural panels.