Crystallization kinetics and microstructure evolution of reduced graphene oxide/geopolymer composites

Reduced graphene oxide/leucite nanocomposites (rGO/leucite) were prepared from reduced graphene oxide/geopolymer composites (rGO/geopolymer) followed by post high-temperature treatment process. The crystallization kinetics and effects of isothermal soaking times on microstructure evolution and mechanical properties of the final rGO/leucite composites were investigated systematically. The results show that the activation energy value for rGO/leucite crystallization was slightly lower than that of pure geopolymer which controlled by a three-dimensional growth mechanism. The scrolled and fold degree of rGO sheets in the rGO/leucite composites increased with the isothermal soaking times. The flexural strength and fracture toughness of the rGO/leucite after treated at 950 °C for 0.5 h reached their maximum values 75.4 ± 5.6 MPa and 1.40 ± 0.03 MPa m1/2, decreased with the isothermal soaking times, respectively.