Permeation of Chlorinated Hydrocarbons Through Nylon 6/Ethylene–Propylene Rubber Blends Soney C. George, 1 K. N. Ninan, 2 G. Geuskens, 3 Sabu Thomas 4 1 Department of Basic Sciences, Amal Jyothi College of Engineering, Koovapally P.O., Kottayam 686518, India 2 Propellant and Special Chemicals Group, PSC Division, VSSC, Thiruvananthapuram 3 Department of Macromolecules, University of Brussels, Campus Plaine, CP 206-1, Boulevard du Triomphe, B-1050 Brussels, Belgium 4 School of Chemical Sciences, Mahatma Gandhi University, Priyadarshini Hills P.O., Kottayam-686 560, India Received 18 February 2003; accepted 1 August 2003 ABSTRACT: Vapor transport offers one the unique ability to study structure–property relationships in polymers. An analysis of the transport of chlorinated hydrocarbons through nylon/ethylene–propylene rubber (EPR) blend membranes showed us how the permeation behavior varied according to the structure and morphology of the material under study. Binary blends were subjected to solvent trans- port studies. The solvent uptake increased with EPR content and decreased with nylon content. The behavior varied with the blend morphology. The effects of blend ratio, compati- bilization, and dynamic vulcanization on the vapor perme- ation behavior of nylon/EPR blends were investigated in detail. The results from the vapor permeation studies were complimentary to those of the morphology studies. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 91: 3756 –3764, 2004 Key words: nylon; rubber; blends INTRODUCTION Vapor permeation has emerged as a new industrial membrane technology. In vapor permeation, the transport of a condensable vapor through a dense membrane consecutive to an activity gradient takes place. This process offers one the unique ability to study the transport process of a single permeant through a dense membrane under various upstream activities. 1 Such characteristics can by no means be obtained by liquid permeation (pervaporation), where the modification of the upstream activity of a compo- nent can only be achieved by the addition of another compound to the mixture; the activity of both compo- nents is modified in this case in compliance with the Gibbs–Duhem relation, which complicates the trans- port analysis. On the contrary, coupling phenomena are not to be considered with pure vapor permeation results. In the case of pure permeation, the upstream activity can easily be calculated if the upstream pres- sure is precisely monitored. 2 In addition to these advantages, a study of solvent vapor permeation offers direct practical conclusions for the understanding and rational design of volatile organic compounds (VOCs) and vapor recovery from contaminated air streams. 3,4 Vapor permeation also offers significant opportunities for energy saving and solvent reuse compared to classical VOC control pro- cesses, such as incineration, oxidation, and active car- bon absorption. In addition to these advantages, the vapor sorption technique is a good tool for the thermodynamic char- acterization of polymer blends. 5,6 The analysis of the equilibrium sorption of a vapor by a blend can pro- vide information on polymer–polymer interactions. The amount of vapor sorbed is related to its interac- tion with the blend. The usual technique for investi- gating the morphology of an immiscible polymer blend is scanning electron microscopy (SEM) applied to the surface of cryofractures. However, that tech- nique gives a picture of only a minute portion of the sample, which is sometimes nonrepresentative of the bulk of the material. Moreover, from a two-dimen- sional picture, it is not easy to estimate when phase inversion occurs as a function of composition and when the level of phase cocontinuity reaches a maxi- mum. Nylon 6 is an engineering thermoplastic character- ized by its high tensile strength, impact strength, toughness, rigidity, abrasion resistance, and resistance to hydrocarbons. It is used mainly in engineering ap- plications. Ethylene–propylene rubber (EPR) is a spe- cialty rubber characterized by excellent aging and weathering resistance. Blends of nylon and EPR are a new class of thermoplastic elastomers that combine the excellent processability characteristics and engi- neering properties of nylon 6 and the elastic and ozone-resistance properties of EPR. These blends ex- Correspondence to: S. C. George (soneygeo@sancharnet.in). Journal of Applied Polymer Science, Vol. 91, 3756 –3764 (2004) © 2004 Wiley Periodicals, Inc.