Sustainable Multifunctional Hybrid Interpenetrating Polymer Network Composites: Evaluating Mechanical and Acoustic Performance of Sisal–E‐Glass–Cenosphere Systems

ABSTRACT Hybrid composites have garnered substantial attentiveness as multifunctional materials, appropriate for a multiplicity of engineering applications. In this study, mechanical and acoustic investigations have been carried out on sisal and E‐Glass fiber reinforced interpenetrating polymer network (IPN) composite with the combination of various proportions of cenosphere particulates such as 0%, 2.5%, 5%, 7.5%, 10%, and 12.5%. In order to explore the explicit benefits of IPNs, the equal volumes of epoxy and vinyl ester (50:50) have been taken into account along with their respective hardeners. As well, IPN laminates are fabricated through the hand lay‐up technique with the intention of ensuring the uniform dispersion of particulates and fibers. Besides, thermal and physical examinations such as dynamic mechanical analysis (DMA), tensile, flexural, impact, heat deflection analysis (HDT) and eventually acoustic performance tests have been conducted as per ASTM standards. The novelty of this work lies in establishing a multifunctional hybrid IPN composite system that achieves concurrent enhancement of mechanical stiffness, thermal stability, and sound absorption through the optimized incorporation of cenospheres (CO). In this connection, the test results indicated that the incorporation of the CO substantially improves the sound absorption, similarly having maintained healthy mechanical properties. In due course, an optimal CO inclusion of 10% has shown exemplary performance as found values in relation to DMA (↑E′—9.01 GPa, ↑E″—0.33 GPa, ↑Tanδ—86.27), tensile (↑313.71 MPa), flexural (↑261.81 MPa), impact (↑27 kJ/m 2 ), HDT (↑89°C), and sound (↑0.5898 at 4000 Hz) absorption are predominantly shown higher values than all remaining set of inclusions. This synergy between lightweight reinforcement and enhanced damping performance proves a new pathway for designing high‐performance, sustainable polymer composites. Additionally, to exactly expose the reason behind that phenomenal hike in strength, specimens are subjected to scanning electron microscopic investigations to better explore the interfacial strength mechanisms.