The measured 𝐸 𝑚 value of 2.48 GPa sits within the expected range of 2.45 -2.55 GPa from the manufacturer. The highest 𝐸 𝑐 achieved was 5.01 GPa for 6.4 wt.% PG-NH loading, an ~100% increase on 𝐸 𝑚 . This percentage change in modulus outperforms all the papers cited in a recent review on 2D material epoxy nanocomposites [67], except for a Ti3CN epoxy nanocomposite with a significantly higher loading of 90 wt.% . The 𝐸 𝑐 increases with loading for all GNPs, apart from for the highest loading PG-NH specimen. This failure to further stiffen the composite, can be attributed to the agglomeration of PG-NH flakes, reducing their effective surface area in the matrix . This is prone to happen at higher loadings as there is more opportunity for flake-flake van der Waals interactions [70],