RUI: Determination of the Free-Volume Size Distributions in Polymeric Materials

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A new spectroscopic approach using the positron annihilation lifetime technique will be used to determine the free-volume hole-size distributions in polymeric materials. The research activities involve: 1) positron lifetime measurements as a function of temperature and pressure in epoxy, poly(vinyl acetate), PMMA and PEEK polymers, and 2) a renaissance of positron lifetime spectroscopy by significantly improving nuclear counting efficiency and instrument resolution, and by employing numerical Laplace inversion techniques to analyze the positron lifetime data. The free-volume hole-size distributions in these selected polymers are to be determined experimentally for the first time as a part of the research.