PSI - Issue 64

Chiara Pepi et al. / Procedia Structural Integrity 64 (2024) 1896–1903 Maria Eleonora Pipistrelli / Structural Integrity Procedia 00 (2019) 000 – 000

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3. Results and Discussion The fibers tensile properties, including tensile strength (i.e. σ MAX ), elastic modulus (i.e. E) and maximum strain ( ϵ MAX ), are estimated. Tensile strength is computed as the load measured at failure and the fiber’s area. Maximum tensile strain is evaluated as the ratio between elongation at failure and the initial length of the fiber. Elastic modulus is evaluated as the secant modulus of the stress-strain curves. Figure 4,a-b shows the experimental stress-strain plots for fibers with 30 minute alkali treatment (red continuous lines) and graphene coating (black dotted lines).

Fig. 2: Examples of SEM images for 24 hours treatment: (a) Spanish broom fiber treated with NaOH; (b) Spanish broom fiber coated with graphene after the alkali treatment; (c) hemp fiber treated with NaOH; (d) ) hemp fiber coated with graphene after the alkali treatment.

Fig. 3. (a) Example of 3 Spanish broom fibers specimens; (b) photo of a sample during the experimental test; (c) photo of the broken sample after the experimental test.