Free Volume Distributions in Ultrahigh and Lower Free Volume Polymers:  Comparison between Molecular Modeling and Positron Lifetime Studies

2002 ◽  
Vol 35 (6) ◽  
pp. 2129-2140 ◽  
Author(s):  
D. Hofmann ◽  
M. Heuchel ◽  
Yu. Yampolskii ◽  
V. Khotimskii ◽  
V. Shantarovich
Keyword(s):  
Molecular Modeling ◽  
Free Volume ◽  
Positron Lifetime ◽  
Lifetime Studies

Free volume and glass transition in ethylene/1-octene copolymers: positron lifetime studies and dynamic mechanical analysis

Polymer ◽  
2002 ◽  
Vol 43 (25) ◽  
pp. 6973-6983 ◽  
Author(s):  
D. Kilburn ◽  
D. Bamford ◽  
T. Lüpke ◽  
G. Dlubek ◽  
T.J. Menke ◽  
...  
Keyword(s):  
Glass Transition ◽  
Dynamic Mechanical Analysis ◽  
Free Volume ◽  
Positron Lifetime ◽  
Mechanical Analysis ◽  
Dynamic Mechanical ◽  
Lifetime Studies

Positron lifetime studies of free volume hole size distribution in glassy polycarbonate and polystyrene

1996 ◽  
Vol 157 (2) ◽  
pp. 351-364 ◽  
Author(s):  
G. Dlubek ◽  
A. P. Clarke ◽  
H. M. Fretwell ◽  
S. B. Dugdale ◽  
M. A. Alam
Keyword(s):  
Size Distribution ◽  
Free Volume ◽  
Positron Lifetime ◽  
Hole Size ◽  
Lifetime Studies ◽  
Free Volume Hole

Positron lifetime studies in organic media

1971 ◽  
Vol 4 (2) ◽  
pp. 261-268 ◽  
Author(s):  
K P Singh ◽  
R M Singru ◽  
C N R Rao
Keyword(s):  
Positron Lifetime ◽  
Organic Media ◽  
Lifetime Studies

Mechanical and microstructural properties of polystyrene based composites: positron lifetime spectroscopic and DSC studies

2011 ◽  
Vol 31 (2-3) ◽  
Author(s):  
Abdullah Mohammed Ali Mohammed Altaweel ◽  
Jaya Madhu Raj ◽  
Malalvalli Nagarajaiah Chandrashekara ◽  
Puttegowda Ramya ◽  
Parthasarathy Sampathkumaran ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Thermal Stability ◽  
Free Volume ◽  
Positron Lifetime ◽  
Tensile Modulus ◽  
Silica Content ◽  
Scanning Calorimetry ◽  
Dsc Studies ◽  
Microstructural Property ◽  
Calcium Aluminosilicate

Abstract Polystyrene (PS) based composites respectively with cenosphere (CS) and calcium aluminosilicate (CAS) as fillers were studied using the positron lifetime technique to reveal the correlation between free volume, a microstructural property, and mechanical properties of the composites (tensile strength and tensile modulus). The thermal stability of the composites was determined using differential scanning calorimetry. The results showed that addition of CAS filler lead to a significant improvement in the mechanical properties of the composite, whereas addition of CS resulted in improvement in tensile modulus only. Both PS/CAS and PS/CS composites showed enhancement in thermal stability compared with that of the pure PS matrix. The positron results showed that the average free volume size for the PS/CAS composite (at 40 phr CAS) was reduced significantly compared with that of the pure PS. These results are understood in terms of the influence of silica content, filler-matrix interaction, and particle size.

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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