Study of Gamma Irradiation Effect on Unplasticized PVC by Positron Annihilation

摘要

Positron annihilation technique is used to study the gamma irradiation effect on unplasticized PVC (UPVC). Positron annihilation lifetime spectroscopy (PALS) results show that both the o-Ps lifetime and intensity decrease with the increase of gamma irradiation dose. By comparing Coincidence Doppler Broadening (CDB) results of four typical polymers using different reference sample, it is confirmed that CDB ratio curve can truthfully reflect the momentum difference of electrons which positrons annihilate with. The CDB results of gamma-irradiated UPVC using non-irradiated UPVC rather than commonly chosen LDPE as a reference sample show obvious oxygen peak, together with FTIR results, verify the appearance of carbonyl groups around the free volume.