High-resolution and high-accuracy calorimetry of order-disorder and melting transitions in the n-alkanes n-pentadecane, n-hexadecane, n-heptadecane, n-octadecane, n-nonadecane and n-eicosane

In this work, a Peltier-element-based adiabatic scanning calorimeter was used to investigate, with highresolution and accuracy, the temperature dependence of the specific heat capacity and specific enthalpy difference of a series of linear alkanes. More specifically, results are reported for the even n-alkanes; namely neicosane, n-octadecane, n-hexadecane and for the odd n-alkanes, namely n-nonadecane, n-heptadecane and npentadecane. The measurements cover a temperature range from well in the crystalline solid phase across the solid-solid transitions (when present) in to the liquid phase across the melting transition. Accurate transition temperatures and heat of transitions were derived from the direct experimental data in view of the potential use of n-alkanes as phase change materials.