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A model study for release of plasticizers from polymer films through vapor phase
Author(s) -
Bellobono Ignazio Renato,
Marcandalli Bruno,
Selli Elena,
Polissi Alessandra,
Leidi Giorgio
Publication year - 1984
Publication title -
journal of applied polymer science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.575
H-Index - 166
eISSN - 1097-4628
pISSN - 0021-8995
DOI - 10.1002/app.1984.070291020
Subject(s) - plasticizer , polymer , saturation (graph theory) , evaporation , vapor pressure , materials science , solubility , chemical engineering , permeation , mass transfer , phase (matter) , analytical chemistry (journal) , polymer chemistry , thermodynamics , membrane , chemistry , organic chemistry , chromatography , composite material , physics , engineering , biochemistry , mathematics , combinatorics
A model has been applied to release of plasticizers from polymer films through vapor phase, for which the overall rate of release may be generally determined by evaporation of the plasticizer from the surface of the film, and/or by migration to the surface at below saturation in the polymer. The experimental system employed made use of n ‐butyl formate, diethyl‐phthalate, di‐ n ‐butylphthalate, and N , n ‐butylbenzenesulfonamide as model molecules in polycaprolactam films, both with the aims of studying undesirable loss of plasticizers, and of simulating a model able to envisage releasing, at a constant rate, of any desired additive, with relatively high solubility and vapor pressure, to the content of packaging films. Experimental measurements were made (at 298–333 K) by investigating in a suitable cell the permeation of plasticizers both at concentrations below and above the saturation limit. Rate of evaporation of plasticizers from the membrane surface above the saturation limit, measured in this cell, were found to coincide satisfactorily with those calculated by application of the mass transfer theory to evaporation from a stationary liquid into a stirred gas, at a known velocity of gas flowing past the surface. From these latter rates and solubilities, the mass transfer coefficients H for evaporation could be obtained, as well as from experimental time lags the diffusivities D p through the polymer membrane. In the light of the theoretical model a correlation was found between activation energies of H and evaporation enthalpies of the model molecules.