Diffusion of Two Associated Solvents in Various Compositions Through a Swelling Polymer Material, EVAc A. Oughilas, 1 O. Roukbi, 1 A. Benghalem, 1 M. Zouaoui Rabah, 1 N. Chafi 2 1 Laboratory of Materials and Catalysis, Faculty of Science, BP 89 University Djillali Liabes of Sid Bel-Abbes, 22000 Sid Bel-Abbes, Algeria 2 Laboratory of Macromolecular and Organic Chemistry, Faculty of Science, BP 89 University Djillali Liabes of Sid Bel-Abbes, 22000 Sid Bel-Abbes, Algeria Received 27 October 2005; accepted 23 March 2006 DOI 10.1002/app.24622 Published online in Wiley InterScience (www.interscience.wiley.com). ABSTRACT: The particular sorption by a swelling poly- mer with the transfer of hydrocarbons was studied in order to evaluate some barrier properties of this material. The transfer of two types of solvents through two varieties of eth- ylene vinyl acetate was investigated: absorption of pure tolu- ene and pure n-hexane and absorption of a toluene/hexane mixture in various compositions. A comparison between the two processes showed that these transfers were very differ- ent and depended on two factors: vinyl acetate content and composition of the mixture. The kinetics of absorption were calculated for various compositions. The profiles of concen- tration as well as the kinetics of swelling were evaluated using a numerical model deduced from the general theory of radial diffusion of a substance with change in dimen- sions. Ó 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 2099– 2106, 2007 Key words: swelling; mixture solvents; polymer; diffusion INTRODUCTION The solution and transport behavior of low-molecu- lar-weight substances in polymeric materials is a topic of interest for many fields of science and technology. The importance and relevance of such behavior has become more apparent in recent years with the accel- erating development of separation membrane systems and highly impermeable or selectively permeable packaging or barrier films and the overall increase in the use of polymeric materials for diverse applications with the consequent exposure to various environmen- tal agents. 1 Polymers are permeable. This may seem to be a disadvantage, in that polymeric containers may allow loss or contamination of their contents and aggressive substances such as water will diffuse into polymeric structures such as adhesive joints or fiber- reinforced composites and cause weakening. How- ever, in some cases permeability is an advantage. One particular area where this is so is the use of polymers in drug delivery systems. These polymers have since been augmented by the introduction of materials such as ethylene vinyl acetate copolymer (EVAc) for intrau- terine devices and various hydrogels, which may be used to construct devices that release larger molecules in a controlled manner. 2 Following the transfer of a diffusing substance through polymer materials, a change in the dimensions of the materials is often observed. The extent of this change depends on the amount of the liquid absorbed. This generally appears with nonporous polymers such as rubbers or elasto- meric materials 3 that can absorb a volume of liquid representing up to 200%–300% of the volume of the polymer free from liquid. There have been many interesting studies of the interdiffusion of two components, liquid or gas, in which volume changes on mixing do or do not occur. The particular sorption by a swelling sheet when only the thickness varies with the transfer of liquid was studied by considering the flux of liquid through sec- tions with respect to the mass of the substance of the sheet. 4 Two dimensionless numbers, known as Debor- ah’s number and the swelling interface number, were thus introduced as criteria for prediction of diffu- sional solute. 5 The kinetics and degree of equilibrium of swelling were studied with different solvents of interpenetrating polymer networks. In this complex system, the number of phases present was found to play a key role, among other factors. 6 The kinetics of swelling of spherical acrylamide gels were deter- mined and studied by considering shear modulus. 7 Few studies have investigated the kinetics of swelling following the diffusion of a liquid through a poly- mer. 8 A good knowledge of the process of the trans- port of liquids controlled by diffusion in which there Correspondence to: A. Benghalem (Benghalem_has@yahoo.fr). Journal of Applied Polymer Science, Vol. 103, 2099–2106 (2007) V V C 2006 Wiley Periodicals, Inc.