Ionic transient species in irradiated poly(vinyl chloride) film

The studies of transient species in irradiated poly(vinyl chloride) (PVC) film have been carried out with the main aim of investigating the charge trapping in a pure system. In PVC, pulse radiolysis gives electron-positive hole pairs. The electron can generate a matrix anion due to the presence of chlorine atom in the PVC macromolecules followed by Cl− detachment. The positive hole may be stabilized as a short-lived matrix cation characterized by visible absorption band with wide maximum in the 350-650 nm range. The positive holes can be scavenged by additives like pyrene, Py and respective radical-ions of Py can be detected. The rate of Py radical cations decay at ∼450 nm was found to be temperature dependent. Two linear parts of the Arrhenius plot were observed which intersected in the 200-240 K range, which is close to the mechanical loss peak connected with the β relaxation in PVC matrix. The activation energies calculated for two parts of Arrhenius plot were equal to 0.40 kJ mol−1 for T < 200 K and 52.6 kJ mol−1 for T > 240 K. The novel mechanism of the ionic and radical reactions in PVC is proposed and discussed.