Bakshi, M.S.Kattimani, S.2026-02-042023Polymer Composites, 2023, 44, 11, pp. 7783-77932728397https://doi.org/10.1002/pc.27665https://idr.nitk.ac.in/handle/123456789/21644Current research focuses on the development of buoyant nanocomposite foams comprising naturally available nanofiller-halloysite nanotubes (HNTs). Cenosphere, a waste byproduct of thermal power plants, is used to impart lightweight properties to syntactic foam composites at 0, 20, and 40 vol% in an epoxy matrix. HNTs are added to the cenosphere epoxy syntactic foam (CESF) composites at a constant 1 vol% to improve the favorable mechanical and water absorption properties of the composites. To evaluate the mechanical response of the CESF and HNTs reinforced syntactic foam (HRSF) composites, compression tests are conducted on samples immersed in water. The results of the water absorption analysis on the CESF and HRSF composites conclude that HNTs inhibit the entry of water into the epoxy matrix, resulting in lower absorption values in HRSF samples than in CESF. Outcomes from the compression tests and FTIR study support this conclusion. The modulus value of the water-immersed HRSF sample with 40% cenospheres (NSF40 W) is reduced by 26.35%, and a 48.52% reduction in the modulus is registered for CESF with a similar concentration without HNTs. Structure–property correlations are established using the crack-pinning phenomenon and planar dispersion of HNTs depicted by transmission electron microscopy. The HNTs reinforcement shows great promise as a structural, buoyant, and lightweight syntactic nanocomposite foam for maritime applications. © 2023 Society of Plastics Engineers.BuoyancyCompression testingFoamsFourier transform infrared spectroscopyHigh resolution transmission electron microscopyKaoliniteNanotubesReinforcementSyntacticsThermoelectric power plantsWater absorption'currentCenospheresCompressive behaviorEpoxyEpoxy matricesFoam compositesHalloysite nanotubesMoisture absorptionNanocomposite foamsSyntactic foamsNanocomposites