▎ 摘　　要

The role of graphene (Gr) and graphene oxide (GO) platelets on microstructure development, shape memory behavior, and electrical conductivity of citric acid-modified thermoplastic starch (CA-modified TPS), prepared by melt mixing, was investigated. The melt linear viscoelastic results showed a greater enhancing effect of Gr platelets on storage modulus of CA-modified TPS nanocomposites compared to that of GO. This together with the highly enhanced stress overshoot observed in the steady shear transient experiments suggested two different roles for the Gr and GO in the microstructure development of TPS nanocomposites. This was evidenced by the electrical conductivity results which showed a pronounced electrical percolation threshold for the TPS-Gr while the TPS-GO samples exhibited an almost linear increase in electrical conductivity with GO content. While, in TPS-Gr, the Gr platelets formed a 3D physical network leading to an electrical percolation, in TPS-GO the greater interfacial interaction between GO and TPS matrix did not allow a 3D network to be formed between GO platelets and GO could only act as reinforcement through enhancing the molecular interconnectivity of TPS. Despite its lower elastic modulus, TPS-GO showed greater shape recovery than that of TPS-Gr. This could be related to higher hydrophilic nature of GO platelets and hence better water absorption of TPS-GO, which is known to act as the dominant parameter in controlling the shape recovery. It was demonstrated that while TPS-Gr is a good candidate for applications where electrical conductivity is a concern, the TPS-GO is suitable for application where shape recovery is a priority.