Influence of Higher Concentrations of Multiwalled Carbon Nanotubes on the Tensile and Flexural Performance of Glass Fiber Reinforced Polymers

The present investigation is an attempt to assess the impact of multiwalled carbon nanotubes (MWCNTs) on the mechanical characteristics of glass fiber reinforced polymer (GFRP) composites. The composites were prepared with epoxy resin as the matrix material and different MWCNT loadings of 1, 1.5, 2, 2.5, and 3 wt% to improve the mechanical properties. The tensile and flexural properties of the composites were determined in accordance with the ASTM test methods D3039 and D790 respectively in order to determine the strength, stiffness, and flexibility of the composites. The findings also indicated that the enhancement of tensile and flexural properties over the neat resin was observed when MWCNTs were incorporated and the highest enhancement was observed at 3 wt% of MWCNTs. At this concentration, the flexural strength was 201.54 MPa and the tensile strength was 130.76 MPa, which showed that the GFRP composite had been significantly reinforced. Nonetheless, when the content of MWCNTs reached more than 1.5 wt%, the tensile strength of the composite decreased due to the poor dispersion of MWCNTs and the formation of agglomerates which reduced the interfacial adhesion and was confirmed by Scanning Electron Microscopy (SEM) analysis. In the study, the importance of dispersion of MWCNT is highlighted as the key to improved composite performance. The outcomes of the study indicate that 3 wt% MWCNT reinforced GFRP composites are ideal for applications that require high strength and stiffness like aerospace and automotive industries while lower concentrations (1.0–1.5 wt %) are ideal for applications that require flexibility and strength in equal measure. This investigation also reveals that MWCNT is a suitable candidate for reinforcement of GFRP composites for different structural applications.