Tuning the mechanical and electrical conductivity properties of graphene‐based thermoplastic starch/poly(lactic acid) hybrids

Environmentally friendly approaches were followed to develop thermoplastic starch (TPS)/poly(lactic acid) (PLA) extruded hybrids at 70:30 and 30:70 compositions, with the incorporation of reduced graphene oxide at 1.0, 3.0, and 5.0 mass% contents. Glucose was chosen as reagent to reduce graphene oxide (GO) to the rGO sample. Theoretical models predicted that the final location of rGO was at the interface of the components. The adhesion between the polymeric phases in the hybrids, observed by scanning electron microscopy, and the improved compatibilization suggested by mechanical and dynamic mechanical analyses indicated that a large fraction of rGO platelets were at the interface. X‐ray diffraction showed that rGO acted as a nucleating agent for PLA and revealed a better dispersion of rGO lamellae within TPS. Consequently, the phase composition of the TPS/PLA/rGO hybrids played an important role on the properties of the hybrids. For the neat TPS/PLA blend at 70:30 composition, ɛ_max = (4.7 ± 0.6)% and the electrical conductivity was found around 10⁻¹³ S/cm. The incorporation of rGO led to more flexible and to higher conductivity materials, with ɛ_max = (15.1 ± 0.7)% and σ = 1.1 × 10⁻⁵ S/cm for the hybrid with rGO at 5.0 mass% content. POLYM. COMPOS., 40:E1131–E1142, 2019. © 2018 Society of Plastics Engineers