Ionic and excited intermediates in pulse-irradiated polypropylene doped with aromatics

A pulse radiolysis study of isotactic polypropylene (PP) film has been carried out with the main aims of investigating charge trapping in an undoped system and solute radical ion generation in an pyrene (Py) doped matrix. In PP, pulse radiolysis gives electron–positive hole pairs. The electron can be stabilized in the undoped system as a trapped electron, e. The transient absorption spectrum of e in the near-IR (up to 1800 nm) was observed in the temperature range 30–100 K. This IR absorption was not detected in the case of oxidized PP. In such a matrix electrons can be scavenged by oxidation products generating respective radical-anions (absorption in the UV RANGE, λ Tg and T < Tg, respectively. Some preliminary results concerning the ionic processes in PP containing two solutes (Py, 3,3′-dimethyldiphenyl) were presented. The mechanism of ionic recombination in PP will be proposed and discussed. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 1217–1226, 1998