AbstractIn this study, thermally and mechanically stable poly(methyl methacrylate) (PMMA)-based nanocomposites were produced through the reinforcement of electrospun aramid-silica-grafted multi-walled carbon nanotube-based nanofibers (MWCNT-Ar-Si). The multi-walled carbon nanotube was initially modified to prepare an isocyanatopropyltriethoxysilane-grafted MWCNT via the sol-gel route using 3-isocyanatopropyl-triethoxysilane and tetraethoxysilane (TEOS). The silica network was developed and linked to MWCNT by hydrolysis and condensation of TEOS. The said isocyanatopropyltriethoxysilane-grafted MWCNT was electrospun with the aramid solution. The electrospun MWCNT-Ar-Si nanofibers (0.1–1 wt.%) were then reinforced in a PMMA matrix. For comparative analysis, PMMA was also reinforced with 0.1–1 wt.% of aramid nanofibers. The tensile modulus of PMMA/MWCNT-Ar-Si 0.1 was 5.11 GPa, which was increased to 13.1 GPa in PMMA/MWCNT-Ar-Si 1. The 10% decomposition temperature of PMMA/MWCNT-Ar-Si 0.1–1 hybrids was in the range of 479–531°C. The glass transition temperature, determined from the maxima of tan δ data using dynamic mechanical thermal analysis, showed an increase with the filler loading and was maximum (301°C) for PMMA/MWCNT-Ar-Si 1 with 1 wt.% of MWCNT-Ar-Si nanofibers. In contrast, PMMA/Ar 0.1–1 hybrids showed lower values in the thermal and the mechanical profile depicting the combined effect of nanotube and aramid in electrospun nanofibers.