Can Positron Annihilation Lifetime Spectroscopy Measure the Free-Volume Hole Size Distribution in Amorphous Polymers?

1995 ◽  
Vol 28 (18) ◽  
pp. 6268-6272 ◽  
Author(s):  
Z. Yu ◽  
J. D. McGervey ◽  
A. M. Jamieson ◽  
R. Simha
Keyword(s):  
Size Distribution ◽  
Positron Annihilation ◽  
Free Volume ◽  
Amorphous Polymers ◽  
Positron Annihilation Lifetime Spectroscopy ◽  
Hole Size ◽  
Positron Annihilation Lifetime ◽  
Free Volume Hole

Free-Volume Hole Properties of Gas-Exposed Polycarbonate Studied by Positron Annihilation Lifetime Spectroscopy

1996 ◽  
Vol 29 (24) ◽  
pp. 7859-7864 ◽  
Author(s):  
X. Hong ◽  
Y. C. Jean ◽  
Hsinjin Yang ◽  
S. S. Jordan ◽  
W. J. Koros
Keyword(s):  
Positron Annihilation ◽  
Free Volume ◽  
Positron Annihilation Lifetime Spectroscopy ◽  
Positron Annihilation Lifetime ◽  
Free Volume Hole

On the Limits of Sensitivity of PALS to Incorporated Free Volume Holes in Polymeric Membranes and Sorbents: Effect of sc-CO2 in Polyhexafluoropropylene

2017 ◽  
Vol 373 ◽  
pp. 261-264 ◽  
Author(s):  
Victor Shantarovich ◽  
Valentin Bekeshev ◽  
Nikolai Belov ◽  
Irina Kevdina ◽  
Mikhail Filimonov ◽  
...  
Keyword(s):  
Low Temperature ◽  
Size Distribution ◽  
Positron Annihilation ◽  
Free Volume ◽  
Polymeric Membranes ◽  
Positron Annihilation Lifetime Spectroscopy ◽  
Membrane Materials ◽  
Positron Annihilation Lifetime

Positron annihilation lifetime spectroscopy (PALS) is a recognized instrument for the studies of size-distribution of nanopores (intrinsic free volume holes FVH) in polymers, particularly membrane materials. The limits of this application in the case of “alien” pores, produced by swelling of poly (hexafluoro propylene) PHFP in the gas (CO2) in super-critical (sc-) state are discussed. The obtained conclusions are controlled by measurements of low temperature gas (N2) sorption (LTGS) and by comparison of the data with the results on permeation of various gases through the PHFP membrane. Attention is payed to relaxation with time of the newly created FVH in the PHFP membrane.

Free-volume hole distributions of polymers by positron annihilation lifetime spectroscopy

1993 ◽  
Vol 03 (C4) ◽  
pp. 233-239 ◽  
Author(s):  
G. H. DAI ◽  
Q. DENG ◽  
J. LIU ◽  
H. SHI ◽  
C. M. HUANG ◽  
...  
Keyword(s):  
Positron Annihilation ◽  
Free Volume ◽  
Positron Annihilation Lifetime Spectroscopy ◽  
Positron Annihilation Lifetime ◽  
Free Volume Hole

Preliminary Positron Lifetime Results on Free Volumes in Cyclodextrins

2010 ◽  
Vol 666 ◽  
pp. 99-102 ◽  
Author(s):  
Maria Fatima Ferreira Marques ◽  
A.M.G. Moreira Da Silva ◽  
P.M. Gordo ◽  
Z. Kajcsos
Keyword(s):  
Positron Annihilation ◽  
Free Volume ◽  
Positron Lifetime ◽  
Positron Annihilation Lifetime Spectroscopy ◽  
Positron Source ◽  
Lifetime Component ◽  
Positron Annihilation Lifetime ◽  
Long Lifetime

Positron annihilation lifetime spectroscopy was used to study the free-volume parameters in various pure -, - and -cyclodextrins samples and, in the case of β-cyclodextrin, with inclusion of S-carvone and thymoquinone. The results clearly indicate the presence of long lifetime components related to Ps-formation. The data show that the addition of S-carvone to β-cyclodextrin results in a decrease of o-Ps lifetime that we ascribe to a reduction of free volume holes from 81.8 to 63.7 Å3. The long lifetime component disappears when thymoquinone is added to -cyclodextrin, indicating this substance acts as an o-Ps quencher. For all samples studied, a decrease in the long lifetime component values was observed with increasing source in situ time, a result that might be attributed to the irradiation of the sample by the 22Na positron source.

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