Thermodynamic assessment of orientationally disordered organic molecular crystals: Ternary system pentaerythritol–neopentylglycol–2-amino-2methyl-1,3, propanediol (PE–NPG–AMPL)

Organic crystals such as pentaerythritol [PE-C(CH2OH)4], neopentylglycol [NPG-(CH3)2C(CH2OH)2] and 2-amino-2methyl-1,3,propanediol [AMPL-(HOCH2)2C(NH2)CH3] store a large amount of thermal energy in their solid state high temperature phases with orientational disorder. There are very few pure compounds of these polyalcohol and amine family that are commercially available exhibiting these properties, leading to limited choices of energy storage materials. Binary and ternary solid solutions allow a wider selection of materials with different phase transition temperature, heat content, and compositions for practical applications. Thermodynamic calculations of the PE–NPG–AMPL system are presented that provide critical thermodynamic data for energy storage systems. Substitutional solution model is used for optimization of interaction parameters. Activities of binaries, ternary isotherms of PE–NPG–AMPL at various temperatures, and pseudo-binary isopleth are presented.