Thermal properties of graphite intercalation compounds with acids

This work is devoted to systematic thermal analysis of first to fifth stages of binary graphite intercalation compounds (GIC) with HNO₃ and ternary GICs with HNO₃–R (R=CH₃COOH, H₃PO₄) by simultaneous TG–DSC thermoanalyses (Netzsch). Thermolysis of GIC leads to the full deintercalation of acid and significant expansion of samples. The thermal properties of co-intercalated GICs-HNO₃-R and the thermal expanding coefficient of GIC depend on the nature of the intercalate. The endopeak at 110–150 °C corresponds to the loss of nitric acid was observed in DSC- curve of binary second to fifth stages of GICs with HNO₃. A wide endopeak which is characterized by the increasing of decomposition temperature in comparison with GIC-HNO₃ was observed in DSC—curve of ternary GIC with HNO₃–CH₃COOH. Thus, acetic acid stabilizes the graphite nitrate matrix. Two endoeffects due to the deintercalation of HNO₃ (110–180 °C) and H₃PO₄ (450–800 °C) were observed in the DSC-curves of co-intercalated GICs with HNO₃–H₃PO₄ of second and third stages. The value of decomposition heat (ΔH) and weight loss decrease with the increasing of the stage number of GICs. The values of ΔH are equal to 0.40–14.8 kJ/g-at C.