Viscoelastic and mechanical characterization of graphene decorated with graphene quantum dots reinforced epoxy composites

Abstract

The article explores viscoelastic and mechanical property analysis of graphene decorated with graphene quantum dots (GDGQD) reinforced epoxy composite. Tensile, nanoindentation, and nano‐dynamic mechanical analysis (DMA) tests were conducted on the composite with 0 to 1 wt% filler variation (an interval of 0.25 wt% maintained). The hardness and elastic modulus for two different loading conditions under a frequency range of 10 to 250 Hz were performed. The viscoelastic properties described through loss tangent and storage modulus graphically and the various factors such as modulus and depth of penetration were influenced by force frequency and mobility of the molecular chain. The results revealed the role of GDGQDs as filler material for enhancing the nanomechanical and tensile properties of the epoxy matrix. The differences in the properties can be ascribed to the filler interfacial bonding with the polymer matrix at the molecular level. The macro‐level properties like tensile properties following the same trend as that of the micro‐level properties like nano‐indentation and nano‐DMA results. Further, with the GDGQD aspect ratio, and assuming three‐dimensionally filled randomly orientation of filler, the Halpin‐Tsai model was satisfied with the experimental tensile modulus values.

A robust and fluorescent nanocomposite hydrogel with an interpenetrating polymer network based on graphene quantum dots

“…The crystallinity was calculated by the following formula: where =138.6 J/g, which represents the heat required for melting a 100% crystalline PVA sample. [ 3 ]…”

“…where ΔH c =138.6 J/g, which represents the heat required for melting a 100% crystalline PVA sample. [3] The fluorescence of the PVA/PNMA/GQDs nanocomposite hydrogel was recorded on a fluorescence spectrophotometer (PELS-55, PerkinElmer). The excitation wavelength was 360 nm.…”

“…Graphene quantum dots (GQDs) are widely employed in chemical sensing, biological fluorescent probes, lightemitting devices, photocatalysis, and nonlinear optical devices because of their distinctive optical property, strong luminescence, low toxicity, chemical inertness, and ease of preparation. [1][2][3] However, the fluorescence of GQDs is weakened, which seriously restricts their applications in solid fluorescent substances. This is because of the non-radiative loss of the excited state caused by the transfer of excessive fluorescence resonance energy and the π-π stacking interaction between the carbon cores.…”