# Thermal properties of 1-butyl-3-methylimidazoliumdicyanamide at high pressures and temperatures

**Marina Engelmann, Hannes Schmidt, Javid Safarov ^{ *}^{ a}, Jürgen Nocke, Egon Hassel**

*Institute of Technical Thermodynamics, University of Rostock,
Albert-Einstein-Str. 2, D-18059 Rostock, Germany ^{a }Department of Heat and Refrigeration Techniques, Azerbaijan Technical University, H. Javid Avn. 25, AZ1073 Baku, Azerbaijan*

**E-mail:** ^{* }javid.safarov@uni-rostock.de

**Abstract:** Thermophysical properties of *1*-*butyl*-*3*-*methylimidazolium dicyanamide*** **[BMIM][DCA] {(*p, *r*, T*) data at *T* = (283.15 to 393.15) K, pressures up to *p *=100 MPa, and viscosity at *T* = (283.15 to 373.15) K and *p *= 0.101 MPa} are reported with an estimated experimental relative combined standard uncertainty of Dr/r = ±(0.01 to 0.08) % in density and Dh/h = ±0.35 % in dynamic viscosity. The measurements were carried out with a recently constructed Anton-Paar DMA HPM vibration-tube densimeter and a fully automated SVM 3000 Anton-Paar rotational Stabinger viscometer. The vibration-tube densimeter was calibrated using double-distilled water, methanol, toluene and aqueous NaCl solutions.

An empiric equation of state for fitting of the (*p, *r*, T*) data of [BMIM][DCA] has been developed as a function of pressure and temperature. This equation was used for the calculation of thermomechanical properties of the IL, such as isothermal compressibility, isobaric thermal expansibility, differences in isobaric and isochoric heat capacities, thermal pressure coefficient and internal pressure. Viscosity measurements were fitted to the polynomial equation.

**Keywords:** Density, viscosity, vibration tube densimeter, equation of state, isothermal compressibility.

*Full paper in Portable Document Format:* acs_0114.pdf

Acta Chimica Slovaca, Vol. 5, No. 1, 2012, pp. 86—94