Synergistic effects of alkali-treated/un-treated banana fiber and groundnut shell biochar on the mechanical, thermal, and morphological performance of epoxy-based hybrid composites

Sustainable and lightweight bio-composites created from natural resources have been the focus areas of modern research due to rising concern about environment. This work examines the development and characterization of sustainable banana fiber (BF) and groundnut shell powder (GSP) reinforced epoxy hybrid composites for lightweight structural applications. Three composite configurations of epoxy, BF and GSP biochar powder were produced utilizing a hand lay-up technique. In the fabricated samples the total reinforcement was kept constant at 30 wt. %, but the BF: GSP ratio was kept at 15:15, 10:20, and 20:10 to assess the influence of the filler distribution. The impact of alkali treatment and filler composition on mechanical, thermal, water absorption, and microstructural properties was assessed. Mechanical testing indicated that the S2 composite having BF: GSP at 10:20 shows better overall performance, with a tensile strength of 83.38 MPa, flexural strength of 94.76 MPa, and a hardness value of 65, and whereas S3 (BF: GSP = 20:10) exhibited the maximum compressive strength at 87.15 MPa and impact strength of 5.3 J/mm. Water absorption test revealed that treated S2 sample absorbs only 5% moisture. Morphological analysis using SEM exhibits that the sample S2 has consistent filler distribution, robust interfacial adhesion, and decreased void formation. FTIR measurement confirmed the effective integration of BF and GSP into the epoxy matrix. Furthermore, the thermogravimetric analysis indicates that samples S2 with higher biochar content has demonstrated superior thermal stability and delayed material degradation. The study also reveals that alkali treated samples exhibits better thermos-mechanical properties.