TIME-RESOLVED RAMAN MEASUREMENTS OF HYDROCARBON INTERACTIONS WITH POLY-ALPHA-OLEFIN FILMS

Laser Raman spectroscopy was used to study the dissolution of volatile hydrocarbon molecules in thin films of poly-alpha-olefin oil. Above t he boiling point of the hydrocarbon, or when no liquid hydrocarbon was present, the dissolution was driven by Henry's law solubilities in li ne with previous models. However, below the boiling point and when sig nificant Liquid hydrocarbon was present, dissolution was entropically driven. Under these conditions, where equilibrium solubilities were no t achievable, the Raman spectra were used to determine hydrocarbons, p ressure and temperature influenced the dissolution rate primarily by a ffecting the vapor pressure and concentration of the volatile hydrocar bon. The rate-limiting step for the dissolution involved mass transpor t at the vapor/film interface.