Passive thermo-elastic behaviour of surface enhanced glass-epoxy composites with spray coated graphene nanoplatelets (GNP)

In the infrared thermography (IRT), computation of the temperature is very important to characterise the defect in a structure and depends upon the thermal signature of that structure. Thermal signature of some low emissive surfaces and sub-surface abnormalities is very small and often lost in the noise. Here, we report an excellent thermo-elastic behaviour of the graphene nanoplatelets (GNP) - Glass Fiber Reinforced Polymer (GFRP) composite beams. GNPs were spray-coated on the GFRP beam with different initial electrical resistances (1 kΩ, 7 kΩ, 21 kΩ and 170 kΩ). The real-time variation in the surface temperature of GNP-GFRP beams, as well as the neat beam, was monitored by IRT under different mechanical loading conditions. We have observed that the GNP-GFRP beam with a number density of GNPs corresponding to the 1 kΩ resistance has shown an increase in the surface temperature by 100% in the uniaxial loading and 300% in the stepped loading and unloading cycles, respectively. Interestingly, the GNP-GFRP beams with a number density of GNPs correspond to 21 kΩ and 170 kΩ have shown a decrease in the temperature as compared to a neat GFRP specimen under the similar loading conditions. These findings are important in the usage of GNPs as smart coatings for the thermal management of the composite surfaces.