Study of Gamma Irradiation Effect on Unplasticized PVC by Positron Annihilation

2017 ◽  
Vol 373 ◽  
pp. 274-279
Author(s):  
Bao Yi Wang ◽  
Jing Yang ◽  
Xing Zhong Cao ◽  
Long Wei ◽  
Run Sheng Yu
Keyword(s):  
Gamma Irradiation ◽  
Positron Annihilation ◽  
Reference Sample ◽  
Irradiation Effect ◽  
Doppler Broadening ◽  
Carbonyl Groups ◽  
Positron Annihilation Lifetime ◽  
Ratio Curve ◽  
Gamma Irradiated ◽  
Coincidence Doppler Broadening

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.

Positron annihilation lifetime and coincidence Doppler broadening study of γ-irradiated polyethylene

2005 ◽  
Vol 313 (1-3) ◽  
pp. 63-69 ◽  
Author(s):  
R.S. Yu ◽  
T. Suzuki ◽  
N. Djourelov ◽  
K. Kondo ◽  
Yasuo Ito ◽  
...  
Keyword(s):  
Positron Annihilation ◽  
Doppler Broadening ◽  
Positron Annihilation Lifetime ◽  
Coincidence Doppler Broadening

Positron Annihilation Studies in Gamma Irradiated Polyesters

2010 ◽  
Vol 666 ◽  
pp. 75-80 ◽  
Author(s):  
Giovanni Consolati ◽  
Mario Mariani ◽  
Fiorenza Quasso
Keyword(s):  
Gamma Irradiation ◽  
Positron Annihilation ◽  
Chain Scission ◽  
Polymer Modification ◽  
Scanning Calorimetry ◽  
Positron Annihilation Lifetime ◽  
Combined Action ◽  
Gamma Irradiated ◽  
Crystallinity Changes ◽  
Physical Changes

Polymerisation and polymer modification are often carried out by means of radiation methods, since irradiation can modify the structure of materials and improve their performance. On the other hand, combined action of ionising radiation and oxygen may induce a degradation of the polymer. Physical changes of different polyesters subjected to gamma irradiation up to 1 MGy are discussed and evidenced by various techniques, mainly viscometry, differential scanning calorimetry and positron annihilation lifetime spectroscopy (PALS). Viscometry monitors variations in the molecular weight. Calorimetric measurements allow one to detect crystallinity changes. PALS evidences possible irradiation effects on the free volume; furthermore, it supplies information on the chemical modifications induced by oxygen. The results can be explained in terms of the main mechanisms induced by gamma irradiation (chain scission, crosslinking and oxydative degradation), although their importance depends on the dose.

Probing Materials by Positron Annihilation Technique and Mossbauer Spectroscopy - Review

2011 ◽  
Vol 699 ◽  
pp. 1-37
Author(s):  
Mahuya Chakrabarti ◽  
S. Chattopadhyay ◽  
D. Sanyal ◽  
A. Sarkar ◽  
D. Jana
Keyword(s):  
Magnetic Properties ◽  
Positron Annihilation ◽  
Room Temperature ◽  
Spectroscopic Studies ◽  
Spectroscopic Technique ◽  
Annihilation Radiation ◽  
Radiation Measurement ◽  
Doppler Broadening ◽  
Positron Annihilation Lifetime ◽  
Coincidence Doppler Broadening

Positron annihilation technique is a well known technique to characterize the defects in a material. These defects can be identified by positron annihilation lifetime and coincidence Doppler broadening of positron annihilation radiation measurement. In this chapter we report the room temperature positron annihilation lifetime for single crystalline ZnO. From our study it is confirmed that the present crystal contains VZn–hydrogen complexes with low open volumes. Another important nuclear solid technique is the Mossbauer Spectroscopic technique which has been used to probe the local magnetic properties of a solid. Here we have summarized Mossbauer spectroscopic studies on ferrites.

Annihilation Lifetime Spectroscopy Using Positrons from Bremsstrahlung Production

2012 ◽  
Vol 331 ◽  
pp. 41-52 ◽  
Author(s):  
Andreas Wagner ◽  
Wolfgang Anwand ◽  
Maik Butterling ◽  
Thomas E. Cowan ◽  
Fine Fiedler ◽  
...  
Keyword(s):  
Positron Annihilation ◽  
Linear Accelerator ◽  
Electron Accelerator ◽  
Positron Annihilation Spectroscopy ◽  
Doppler Broadening ◽  
Electron Linear Accelerator ◽  
Positron Annihilation Lifetime ◽  
Electron Bremsstrahlung ◽  
New Type ◽  
Set Up

A new type of a positron annihilation lifetime spectroscopy (PALS) system has been set up at the superconducting electron accelerator ELBE [ at Helmholtz-Zentrum Dresden-Rossendorf. In contrast to existing source-based PALS systems, the approach described here makes use of an intense photon beam from electron bremsstrahlung which converts through pair production into positrons inside the sample under study. The article focusses on the production of intense bremsstrahlung using a superconducting electron linear accelerator, the production of positrons inside the sample under study, the efficient detector setup which allows for annihilation lifetime and Doppler-broadening spectroscopy simultaneously. Selected examples of positron annihilation spectroscopy are presented.

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