Effects of composition and external electric field on positronium formation in a polymer blend system

Kobayashi, Yoshinori; Wang, CL; Hirata, Koichi; Zheng, W.; Zhang, C

doi:10.1103/physrevb.58.5384

Cited by 67 publications

(65 citation statements)

References 20 publications

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“…Since the concentrations of the electronaccepting SO 3 H groups for chemical inhibition of Ps are unchanged and free space favorable for Ps formation are only in the amorphous regions of the two membranes, Ps formation is expected to rise with decreasing crystallinity. [19,[34][35][36] WAXD patterns confirm the increase of crystallinity for both the samples after heating up to 160 8C ( Figure 5); the crystalline peak around 2u ¼ 178 intensifies and the amorphous peak over 2u ¼ 12-208 weakens. This is qualitatively consistent with the vibration of I 3 as a function of temperature.…”

Section: Discussionmentioning

confidence: 60%

See 1 more Smart Citation

Impact of Heating on the Structure of Perfluorinated Polymer Electrolyte Membranes: A Positron Annihilation Study

Hamed

Kobayashi

Kuroda

et al. 2011

Macro Chemistry & Physics

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The ortho‐positronium (o‐Ps) lifetime was measured as a function of temperature for the perfluorinated PEMs Nafion NR212 and Aquivion E8705. The o‐Ps lifetime in Aquivion E8705 was found to be shorter than Nafion NR212 in the entire temperature range studied. Abrupt changes in the temperature coefficient of the o‐Ps lifetime were noticed and the α‐relaxation, β‐relaxation, and stress relief temperatures were identified. It turned out that Aquivion E8705 has higher α‐relaxation and stress relief temperatures than Nafion NR212. Dissociation of the ionic clusters and large change in the nanostructure after heating to 160 °C were observed for Nafion NR212 but not for Aquivion E8705. It is demonstrated that Aquivion E8705 has a higher thermal stability than Nafion NR212. magnified image

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Section: Discussionmentioning

confidence: 60%

“…[18] They capture electron-positron pairs, which would otherwise recombine with each other to Ps in the positron spur, [19][20][21][22] to appreciably reduce I 3 of the membranes from the value of PTFE without SO 3 H.…”

Section: Resultsmentioning

confidence: 99%

Impact of Heating on the Structure of Perfluorinated Polymer Electrolyte Membranes: A Positron Annihilation Study

Hamed

Kobayashi

Kuroda

et al. 2011

Macro Chemistry & Physics

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“…This paper concerns the application of positron annihilation techniques to identify the effects of polar groups with a dipole distribution of electric charge in polymer chains and the extent to which those effects may be modified in polymer blends [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16].…”

Section: Introductionmentioning

confidence: 99%

Influence of polar groups in binary polymer blends on positronium formation

et al. 2013

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The present work studied the role of the polar group unconjugated oxygen on the inhibition of positronium (Ps) formation in two binary blends made from a set of chosen constituent polymers with polar and weakly polar groups (nonpolar). The polymer blend samples of PVC-EVA and PVC-SAN were investigated by coincidence Doppler broadening and positron lifetime techniques. The strong polar acetate group in the EVA contributed to positron annihilation with electrons of unconjugated oxygen (-C + =O − ) as revealed by the momentum distribution curves peaking around 17 P L (10 −3 m 0 c). The ortho-Ps intensity indicated the unconjugated oxygen shows about a 28% Ps reduction even in the presence of a strong Ps inhibiting halogen (Cl − ). In contrast, this effect was not seen in the PVC-SAN blends since SAN contains a weakly polar (nonpolar) acrylonitrile group (C≡N). Our results indicate the chlorine of PVC in the blends is a major contributor to Ps inhibition through the formation of a (Cl − -e +) bound state but the unconjugated oxygen in EVA of the PVC-EVA blend also plays a similar, but lesser, role.

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“…As is evidenced by the high positron mobility in PE [11], this polarity effect is small for the C group, in which positron annihilation with the electrons of carbon atoms is most probable in light of the fact that the number of electrons bound to hydrogen is much smaller than the number of electrons on carbon atoms. The dips observed for PES and ETFE in the positron age around 0.6 ns well agree with the S−I 3 correlation (see Fig.…”

Section: Resultsmentioning

confidence: 95%

Positron and Positronium Annihilation in Polymers Studied by Age-Momentum Correlation Spectroscopy

et al. 2008

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Positron (e + ) and positronium (Ps) annihilation processes in polymers are studied by positron age-momentum correlation spectroscopy, which can sensitively probe momentum distributions of e + , p-Ps, and o-Ps. For polyether sulfone and ethylene tetrafluoroethylene copolymer belonging to oxygen-containing polymers (O group) and fluorine-containing polymers (F group), respectively, significant effects of positron trapping by polar element are observed. The Doppler profile of o-Ps pick-off annihilation is strongly influenced by F atoms, giving rise to anomalous broadening. The results are discussed together with our previous data of the S−I 3 correlation in order to explore the feasibility of chemical analysis around the free volumes by age-momentum correlation spectroscopy.

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Effects of composition and external electric field on positronium formation in a polymer blend system

Cited by 67 publications

References 20 publications

Impact of Heating on the Structure of Perfluorinated Polymer Electrolyte Membranes: A Positron Annihilation Study

Impact of Heating on the Structure of Perfluorinated Polymer Electrolyte Membranes: A Positron Annihilation Study

Influence of polar groups in binary polymer blends on positronium formation

Positron and Positronium Annihilation in Polymers Studied by Age-Momentum Correlation Spectroscopy

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