Papers Published

1. Jones, P.L. and Hill, A.J. and Pearsall, G.W. and Lind, J.H., A positron annihilation lifetime study of poly(bisphenol-A carbonate), Characterization of Defects in Materials Symposium (1987), pp. 29 - 34 .
   (last updated on 2007/04/10)

   Abstract:
   Positron annihilation lifetime spectroscopy has proven to be sensitive to glass transitions and other free volume dependent phase transitions in amorphous and semicrystalline polymers. The thermal dependence of the lifetime spectra of positrons in compression-molded poly(bisphenol-A carbonate) has been measured from 253 K to 323 K, then modelled using a three component fit. The longest-lived component lifetime τ₃ was found to vary linearly with increasing temperature independent of thermal history. The corresponding component intensity I₃ was found to vary in a non-linear fashion with increasing temperature, exhibiting a significant dependence on thermal history. The observed thermal response of τ₃ and I₃ is discussed in terms of both molecular relaxation and the ductile-to-brittle transition behavior of poly(bisphenol-A carbonate)

   Keywords:
   ductile-brittle transition;polymers;positron annihilation in liquids and solids;