Mechanical properties of hybrid graphene nano platelet-nanosilica filled basalt fibre reinforced polymer composites / Ummu Raihanah Hashim

The emergence of natural fibre composites (NFC) owing to their encouraging properties such as good mechanical properties, availability and environmental friendly has brought to the development of green composites in various applications. Basalt fibre (BF) is one of the promising reinforcing natural material as an alternative to glass fibre due to their comparable properties. It is primarily used in high-end application, which usually requires the use of autoclave in resin transfer moulding (RTM) with high temperature curing resin. The use of BF with fast-cured resin or out of autoclave process are still limited as this could affect the strength of Fibre Reinforced Polymer (FRP) composite. The use of nanofillers in polymer composites are very efficient to enhance the mechanical properties of the composites. The discovery of graphene has extensively brought the material world to a new level as this amazing carbon material could create superior composite properties. However, the challenge to use this material is mainly on its dispersion state and aggregation in epoxy due to its high surface area and strong Van der Waals forces between each graphene sheets. Other than functionalization, one of the effective way to improve the graphene’s dispersion is by introduction of other nano or micro-scale filler. Hence, by adopting the good dispersive nanosilica and its advantages, this study was conducted to evaluate the thermo-mechanical properties of hybrid Graphene Nanoplatelet (GNP)-Nanosilica (NS) in epoxy composites by conducting the Thermogravimetric Analysis (TGA), Dynamic Mechanical Analysis (DMA), tensile, compression, and flexural tests. The solvent-exchange, sonication and high-shear milling methods were used to mix the GNP and NS in epoxy matrix. Then, the hybrid nanofiller modified epoxy polymers were impregnated into BF to evaluate the mechanical properties of the BFRP system under the tensile, compression, flexural, and drop-weight impact tests. In response to the synergistic effect of zero-dimensional NS and two-dimensional GNP, the thermal properties of hybrid nanofiller modified epoxy polymers were improved as the nanofiller loading increased, with the maximum degradation temperature of hybrid system increased by 0.6% for H0.1, 1% for H0.2 and 1.1% for H0.3 as compared to unmodified epoxy polymer. The glass transition temperature (Tg) of the hybrid nanofiller modified epoxy system were increased by 10.3%, 10.2% and 10% for H0.1, H0.2, and H0.3, respectively to compare with unmodified epoxy due to good nanofillers dispersion state in epoxy resin. The mechanical properties of hybrid nanofiller modified epoxy showed that the highest increment in modulus were observed in highest filler system which is H0.3 with 58% improvement in tensile, 36% in compression, and 43% in flexural, respectively, compared to unmodified epoxy. It was found that good dispersion system exhibited the highest strength where H0.2 showed the highest tensile strength of 101.45MPa, while H0.1 showed highest compressive and flexural strength of 298.24MPa and 195.65MPa, respectively. A significant improvement in mechanical properties of BFRP with hybrid nanofiller were also observed especially in BF-H0.2 with highest increment in modulus and strength to compare with neat BF. These findings also revealed that the incorporation of hybrid nanofiller contributed to the improvement in the mechanical properties of the composite, and BF have the potential to be used as a maintenance repair material for structural component as an alternative to the synthetic glass fibre.