The following are major steps in theoretical development in this area. introduced this parameter. Then Prausnitz, with co-workers, split the parameter into two components related to the forces hidden in the enthalpy of a transition process. Hansen 14,15,71 further suggested using the three-component splitting of the cohesion parameter. Hansen defined the solubility parameter (HSP or HSPiP) as cohesive energy density, which keeps molecules together in a liquid or solid state. The HSP can be used to evaluate the relative role of polar, non-polar(dispersion), and hydrogen cohesive forces in a chemical composition.