Ensuring the potential of Caryota urens fruit stem fibre as biodegradable reinforcement for polymer composite structural applications

The work deals with the extraction and characterization of fibre from the unexplored Caryota urens fruit stem (CUFS). The spadix of Caryota urens (CU) has compound spadix inflorescence with a core and branching fruit stems covered by a boat-shaped spathe. The ripened fruit stems of the spadix after the removal of peripheral fruits and their residues are used for fibre extraction process. The fibre from the fruit stem is extracted by soaking it in portable water and then pounded. The mechanical and physical properties of the unexplored CUFS are quantified by tensile test, XRD analysis, SEM, FTIR spectroscopy, and TGA analysis to ascertain their ability to be a reinforcement for bio-composites. The maximum tensile strength and strain of 10 mm fibre are 11 N and 9.9%. The XRD analysis records a 63.39% crystallinity index and a 5.078 nm crystal size. The TGA recorded the thermal stability of fibre at 250 °C with a mass reduction rate of 5.35% per min. The SEM and FTIR report the favourable features of fibre towards adhesion and interfacial bonding with the matrix. Such quantified fibres are woven as unidirectional mats and treated by silane to four variants of epoxy laminates with and without Sisal hybridization. The laminate configurations F1 and F3 are 4 layers of CUFS mat without and with silane treatment, whereas F2 and F4 represent hybridization with Sisal (Sisal/CUFS/CUFS/Sisal) and silane treated, respectively. The silane treatment has significantly improved the storage modulus of the CUFS fibre composite up to 36.96% and the CUFS–Sisal hybrid composite to 128%. The tensile strength of the silane-treated laminate (F3) has increased by 12% over the untreated (F1) laminate attributed to the effect of fibre sizing. However, the combined effect of silane treatment and hybridization has witnessed a 67.7% rise in tensile strength (F4). These characteristics of CU fruit stem fibre ensure the profound calibre to be a potential reinforcement in bio-composite for lightweight structural applications.