Sorption of Volatile Compounds by Polypropylene Film

Abstract

Several kinds of pouches (Polyethylene terephthalate (PET)/Aluminum foil (Al)/Polypropylene (PP)) were filled with a model flavour solution, containing 40 kinds of volatilecompounds. The effect of film characteristics and structure of volatile compounds on thesorption was investigated in order to elucidate the sorption behaviour of volatile compoundsinto polypropylene liner. (1) The distribution ratios (content in film/solution) were greatlyinfluenced by functional groups of the volatile compounds. The distribution ratios becameincreased as follows; alcohols<aldehydes<esters<terpene hydrocarbons. (2) In homolo-gous series of esters and aldehydes, the plots of distribution ratios gave a straight-line ploton semi-log coordinates and the slope indicated that distribution ratios increased aboutthreefold for each methylene group. However, for the compounds composed of 10 or morecarbon atoms, the increments in distribution ratios were less or negative. (3) Comparingsolubility and diffusion coefficients in PP with those in PE film, the solubility coefficient inPP was larger than that in PE by a fator of about 1.2, but diffusion coefficient in PP was atwentieth of that in PE. As a result, volatile compounds were much sorpted into PP filmunder sorption equilibrium, although the sorption proceeded slowly.