Correlation between Gas Diffusion Coefficient and Positron Annihilation Lifetime in Polymers with Rigid Polymer Chains

2000 ◽  
Vol 33 (15) ◽  
pp. 5513-5517 ◽  
Author(s):  
Kazuhiro Tanaka ◽  
Toshinao Kawai ◽  
Hidetoshi Kita ◽  
Ken-ichi Okamoto ◽  
Yasuo Ito
Keyword(s):  
Diffusion Coefficient ◽  
Positron Annihilation ◽  
Gas Diffusion ◽  
Polymer Chains ◽  
Positron Annihilation Lifetime ◽  
Rigid Polymer

Positron Lifetime Annihilation Study of Porous Composites and Silicas Synthesized Using Polymer Templates

2017 ◽  
Vol 373 ◽  
pp. 280-283
Author(s):  
Marek Gorgol ◽  
Agnieszka Kierys ◽  
Radosław Zaleski
Keyword(s):  
Composite Materials ◽  
Porous Structure ◽  
Positron Annihilation ◽  
Positron Lifetime ◽  
Polymer Chains ◽  
Positron Annihilation Lifetime ◽  
Hydrophobic Polymers ◽  
Polymer Templates ◽  
Chemical Character ◽  
Porous Composites

The porous structure of polymer-silica composites, based on three polymer templates, which differ in a porosity and hydrophobicity, was examined using positron annihilation lifetime spectroscopy. Additionally, the investigation of silicas obtained after removal of polymers during calcination of composite materials, was performed. In composites based on hydrophobic polymers, silica condensates only in larger free volumes, while SiO2 deeply penetrates spaces between polymer chains, when the template is polar. Moreover, the structure of the silica gel, obtained after polymer removal, depends on chemical character of the template, rather than its porosity.

scholarly journals Comparison of the free volume sizes and shapes determined from crystallographic and PALS data

Nukleonika ◽  
2015 ◽  
Vol 60 (4) ◽  
pp. 771-775 ◽  
Author(s):  
Maciej Tydda ◽  
Bożena Jasińska
Keyword(s):  
Diffusion Coefficient ◽  
Chemical Composition ◽  
Positron Annihilation ◽  
Molecular Crystals ◽  
The Other ◽  
Complex Chemical ◽  
Positron Annihilation Lifetime ◽  
Complex Chemical Composition ◽  
Crystallographic Structures ◽  
Good Agreement

Abstract Two different classes of molecular crystals were investigated. The first group was benzenediols, which are characterized by the same chemical composition but a different organization of their crystallographic structures; all of the compounds from this group have only one kind of free volumes. The second class was represented by olanzapine, which has more complex chemical composition and two kinds of free volumes in the structure. The o-Ps lifetime values determined from positron annihilation lifetime spectroscopy (PALS) measurements agree quite well with those calculated for sizes found from crystallographic data for benzenediols (agreement within 10% of the lifetime values). For olanzapine, a good agreement is observed in the case of cuboidal free volumes, while for the other kind of void, the agreement is less satisfactory. Positronium diffusion coefficient determined from o-Ps redistribution in olanzapine agrees with these found for polymers.

Assessment of the soil CO2gradient method for soil CO2efflux measurements: comparison of six models in the calculation of the relative gas diffusion coefficient

Tellus B ◽  
2010 ◽  
Vol 62 (1) ◽  
Author(s):  
Natchaya Pingintha ◽  
Monique Y. Leclerc ◽  
John P. Beasley ◽  
Gengsheng Zhang ◽  
Chuckree Senthong
Keyword(s):  
Diffusion Coefficient ◽  
Gas Diffusion

Seeking the Good Fitting Procedure of PALS Polymer Spectra

2008 ◽  
Vol 607 ◽  
pp. 64-66
Author(s):  
Nicolas Laforest ◽  
Jérémie De Baerdemaeker ◽  
Corine Bas ◽  
Charles Dauwe
Keyword(s):  
Experimental Data ◽  
Low Temperature ◽  
Positron Annihilation ◽  
Physical Meaning ◽  
Lifetime Measurements ◽  
Positron Annihilation Lifetime ◽  
Fitting Procedure ◽  
Fitting Procedures ◽  
Blob Model

Positron annihilation lifetime measurements on polymethylmethacrylate (PMMA) at low temperature were performed. Different discrete fitting procedures have been used to analyze the experimental data. It shows that the extracted parameters depend strongly on the fitting procedure. The physical meaning of the results is discussed. The blob model seems to give the best annihilation parameters.

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