Thermodynamic properties of carbynoid structures in the 0—340 K range

The temperature dependences of the heat capacity (Cp°) of carbynoid structures prepared by alkaline dehydrochlorination of poly(vinylidene chloride) and 1,1,2- and 1,2,3-polytrichlorobutadienes were studied by adiabatic vacuum calorimetry between 5 and 340 K with an accuracy of ∼0.2%. The low-temperature relaxation transitions and abnormal patterns of the Cp° vs.T dependences were identified and characterized. The experimental results were used to calculate the thermodynamic functions Cp°(T), H°(T) – H°(0), S°(T) – S°(0), and G°(T) – H°(0) for 0—340 K. These data were compared with the corresponding data for carbyne produced by oxidative dehydropolycondensation of acetylene, which is a mixture of amorphous α- and β-forms with a minor impurity of crystals of both forms.