Conductive epoxy composites are of great interest due to their applications in electronics. They are usually made by mixing powdered conductive fillers with epoxy. However, the conductivity of the composite is limited by the low filler content because increasing filler content causes processing difficulties and reduces the mechanical properties of the epoxy host. We describe here the use of ultra-stiff graphene foams (uGFs) as three-dimensional (3D) continuous conductive fillers for epoxy resins. The powder metallurgy method was used to produce the dense uGFs monoliths that resulted in a very high filler content of 32 wt % in the uGF–epoxy composite, while the density of epoxy was only increased by 0.09 g/cm3. The composite had an electrical conductivity of 41.0 ± 6.3 S/cm, which is among the highest of all of the polymer-based composites with non-conductive polymer matrices and comparable with the conductive polymer matrices reported to date. The compressive modulus of the composite showed a remarkable improvement of >1700% compared to pure epoxy. We have demonstrated that the 3D uGF filler substantially improves the conductivity and reinforces the polymer matrix with a high filler content while retaining a density similar to that of the epoxy alone.

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In this study, thin carbon nanotube (CNT) buckypapers (BPs) with desired porosity were prepared by using of positive pressure filtration method. The obtained porous BP was then directly incorporated into the middle interface of a composite laminate to improve the interlaminar fracture toughness. Double cantilever beam and end-notch flexure tests were conducted to examine the influence of the obtained BP on mode I and mode II interlaminar fracture toughness (G IC and G IIC ) of the laminates. Results have shown the porous BPs would significantly enhance the G IC and G IIC up to 74% and 82%, respectively. Improved interfacial bonding and increased large fracture surfaces were obtained for the laminate incorporated with thin CNT BPs. Similar enhancement was also detected in acoustic emission energy variation for mode II fracture and auxiliary proved the reinforcing effect of the BP.

This study introduces carbon nanotube buckypaper (CNTBP) into the easily fractured sites of [0°]16 and [0°/90°]4S composite laminates, and comparatively explores how the CNTBP affects the flexural properties of the laminates at 25, −15, and −55 °C. Compared to the base [0°]16 and [0°/90°]4S laminates at the same temperature, improvements of the flexural strengths in the order of 4.0–15.3% and 6.5–31.0% are respectively obtained from the corresponding CNTBP‐reinforced [0°]16 and [0°/90°]4S laminates. Importantly, the lower the temperature is, the higher the strength improves. In fact, the CNTBP has little effect on the flexural moduli of the studied laminates, although there is an increasing trend with decreased temperature. Moreover, the introduced CNTBP would significantly change the fracture mechanism of the laminates at low temperature. The present work reveals that the CNTBP exhibits more positive reinforcing capability to the polymer matrix‐based composite laminates at relatively low temperatures.