Showing papers by "Ramón Catalá published in 1996"
TL;DR: Isostatic and quasi-isostatic permeation experiments were used to characterize the permeability of 1-hexanol through polypropylene films as discussed by the authors, and the quasi- isostatic method was considered as an isostastic experiment at the limit a of null purging stream flow rate.
Abstract: Isostatic and quasi-isostatic permeation experiments were used to characterize the permeability of 1-hexanol through polypropylene films. The quasi- isostatic method was considered as an isostatic experiment at the limit a of null purging stream flow rate. Permeability values obtained through the isostatic method showed dependency on the purging stream flow rate. The extrapolated value at zero purging stream flow rate is in agreement with the data obtained via the quasi-isostatic procedure. Diffusion coefficient values were also determined. The isostatically obtained diffusion coefficients behave similarly to P. However, the value at zero flow rate differs significantly from the value obtained through the quasi-isostatic method. From these results the validity of permeation experiments for the evaluation of the diffusion coefficient is questioned.
30 citations
TL;DR: PVdC and aluminium foil (or aluminium metallization) have traditionally been used as flexible high barrier materials in the design of packages for perishable foodstuffs and during recent years new pol...
Abstract: PVdC and aluminium foil (or aluminium metallization) have traditionally been used as flexible high barrier materials in the design of packages for perishable foodstuffs. During recent years new pol...
19 citations
TL;DR: In this paper, the authors used inverse gas chromatography to determine the sorption isotherms of alcohols in EVOH copolymers below and above the glass transition temperature.
Abstract: Sorption isotherms of alcohols in EVOH copolymers were determined by inverse gas chromatography below and above the glass transition temperature. The sorbates studied were : methanol, ethanol, n-propanol, i-propanol, n-butanol, i-butanol, s-butanol, and t-butanol. From the sorption isotherms, Henry's law solubility coefficients (S) were evaluated and correlated to size, condensability, and OH position in the molecule as well as on temperature. Molecular dimension was an important factor, affecting the solubility via two contrary effects : molecular size and condensability. When comparing alcohols of the same size, primary alcohols were sorbed more than secondary alcohols and these more than tertiary alcohols at every temperature in the study. At low temperatures, the larger the size the greater the solubility, contrary to what was observed at high temperatures. Temperature effect on solubility was also tested applying Van't Hoff's equation. Since S behaved differently below and above T g for every sorbate two values of the enthalpy of solution were obtained, positive above T g and negative below T g .
17 citations