Papers Published

  1. Hill, A.J. and Jones, P.L. and Lind, J.H. and Pearsall, G.W., A positron annihilation lifetime study of isothermal structural relaxation in bisphenol-A polycarbonate, J. Polym. Sci. A, Polym. Chem. (USA), vol. 26 no. 6 (1988), pp. 1541 - 52 .
    (last updated on 2007/04/10)

    Abstract:
    Positron annihilation lifetime spectroscopy has been used to study the isothermal relaxation response of compression molded bisphenol-A polycarbonate at temperatures of 263, 273, and 303 K. The temperature dependence of both the lifetime and intensity of the ortho-Positronium (o-Ps) pickoff component is discussed in terms of ductile-to-brittle transition behavior and free volume theory. An additive exponential model and the Williams-Watt model were used to analyze the relaxation as a function of temperature and provided results consistent with the anticipated molecular mobility of polycarbonate at sub-Tg temperatures

    Keywords:
    ductile-brittle transition;polymer structure;positron annihilation in liquids and solids;stress relaxation;