Development of nanosilica and epoxy terminated butadiene acrylonitrile toughened glass fiber reinforced polymer laminates with improved mechanical impact and thermal performance

This study investigates the development of nanosilica/epoxy-terminated butadiene acrylonitrile (ETBN) hybrid toughened glass fiber reinforced polymer (GFRP) laminates with improved mechanical, impact, and thermal performance. Bidirectional E-glass/epoxy laminates were fabricated by vacuum-assisted hand lay-up using a constant ETBN content of 1 wt% and varying nanosilica loadings of 0, 0.5, 1, 2, and 4 wt%. The procured nanosilica was characterized by HRTEM, SEM, XRD, FTIR, and XPS, confirming its amorphous nature, surface siloxane/silanol functionalities, and high chemical purity. Mechanical performance was evaluated through tensile, flexural, Charpy impact, and Barcol hardness tests, while DSC and TGA were used to assess its thermal behaviour. The results showed that nanosilica incorporation significantly influenced laminate performance, with 2 wt% nanosilica providing the best overall balance of properties. The optimum laminate exhibited an ultimate tensile strength of 323 MPa and a Young’s modulus of 2.31 GPa, while flexural strength reached a maximum value of 255.8 MPa at 1 wt% nanosilica and flexural modulus peaked at 14.1 GPa at 2 wt%. Toughness and impact resistance also improved up to 2 wt% nanosilica, whereas hardness was highest at low-to-moderate loadings (0.5–1 wt%). At 4 wt% nanosilica, property deterioration was observed due to agglomeration and non-uniform dispersion. ANN-based multi-response optimization performed in MATLAB further validated 2 wt% nanosilica as the optimum composition, with the best validation performance obtained at epoch 3 (MSE = 6.6211).