STP1237

    Effects of Biaxial Tensile Strain on Hydrocarbon Permeability of Butyl Rubber Composite Barriers

    Published: Jan 1996


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    Abstract

    A study has been initiated to assess hydrocarbon permeability of carbon black-reinforced butyl rubber composite barrier under planar biaxial tension. In simulation of externally applied physical strain during the usage of protective clothing, biaxially-stretched barrier specimens were exposed to the challenging agent of 1,5-dichloropentane. The results of permeation tests indicated that the decrease of breakthrough time under external strain stems exclusively from the reduction of barrier thickness. On the other hand, the steady-state permeation rate of butyl rubber composite was found to be dependent on the level of tensile strain as well as the reduction of barrier thickness. Thickness dependence of steady-state permeation rate became greater with higher extension ratios. The observed pure strain effect on the permeability was further analyzed by estimating the values of diffusion coefficient and solubility. The diffusion coefficient of composite barrier system was found to be independent of the level of strain applied. However, the solubility of the system was clearly increased by the external strain. The phenomenon could be attributed to two possible mechanisms. First, external strain can increase equilibrium swelling of butyl rubber matrix and thereby raise the solubility of the system. Additionally, the application of external strain can induce local debonding of carbon black reinforcement from the matrix of composite barrier system. The formation of local debonding sites is expected to accelerate the permeation process, since the vacuoles created are accessible to the solvent uptake.

    Keywords:

    permeability, butyl rubber, elastomer barrier, biaxial tensile strain, hydrocarbon, diffusion, solubility, swelling


    Author Information:

    Lee, BL
    Associate Professor and research assistant, The Pennsylvania State University, University Park, PA

    Yang, TW
    Associate Professor and research assistant, The Pennsylvania State University, University Park, PA

    Hassler, KD
    Chemist and Chief of Materials & Polymer Applications Branch, Army Natick Research, Natick, MA

    Wilusz, E
    Chemist and Chief of Materials & Polymer Applications Branch, Army Natick Research, Natick, MA


    Paper ID: STP14065S

    Committee/Subcommittee: F23.93

    DOI: 10.1520/STP14065S


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