The Free Volume in Dried and H2O-Loaded Biopolymers Studied by Positron Lifetime Measurements

2014 ◽  
Vol 118 (31) ◽  
pp. 9356-9360 ◽  
Author(s):  
Christoph Hugenschmidt ◽  
Hubert Ceeh
Keyword(s):  
Free Volume ◽  
Positron Lifetime ◽  
Lifetime Measurements

scholarly journals POSITRON LIFETIME MEASUREMENTS IN NATURAL RUBBER WITH DIFFERENT FILLERS

2013 ◽  
Vol 22 ◽  
pp. 112-117 ◽  
Author(s):  
A. MANDAL ◽  
S. MUKHERJEE ◽  
S. PAN ◽  
A. SENGUPTA
Keyword(s):  
Natural Rubber ◽  
Positron Annihilation ◽  
Free Volume ◽  
Positron Lifetime ◽  
Amorphous Region ◽  
Filler Concentration ◽  
Lifetime Measurements ◽  
Positron Annihilation Lifetime

Positron annihilation lifetime spectra (PLAS) have been measured for natural rubber polymer with different fillers (Titenium dioxide, Nanosilica and Nanoclay) as a function of filler concentration to investigate how these fillers affect the microstructure of free volume of natural rubber. The lifetime spectra is analyzed by using LT9.0 and the longest lived component(τo-Ps) is attributed to the pick- off annihilation of o-Ps in free volume sites, available mostly in the amorphous region of polymer. On the basis of the τo-Ps values the radii of the free volume holes (Rh) are calculated. The PALS results show that o-Ps lifetime as well as the size of free volume decreases with the increase of filler concentration.

Characterization of free volume and density gradients of polystyrene surfaces by low-energy positron lifetime measurements

Polymer ◽  
2004 ◽  
Vol 45 (13) ◽  
pp. 4533-4539 ◽  
Author(s):  
John Algers ◽  
Ryoichi Suzuki ◽  
Toshiyuki Ohdaira ◽  
Frans H.J. Maurer
Keyword(s):  
Free Volume ◽  
Positron Lifetime ◽  
Low Energy ◽  
Density Gradients ◽  
Lifetime Measurements

scholarly journals Study of interfaces in polymer-metal oxide films and free-volume hole using low-energy positron lifetime measurements

2019 ◽  
Vol 4 (3) ◽  
pp. 413-419 ◽  
Author(s):  
Aman Deep Acharya ◽  
Bhawna Sarwan ◽  
Ratnesh Sharma ◽  
S.B. Shrivastava ◽  
Manoj Kumar Rathore
Keyword(s):  
Metal Oxide ◽  
Free Volume ◽  
Positron Lifetime ◽  
Oxide Films ◽  
Low Energy ◽  
Metal Oxide Films ◽  
Lifetime Measurements ◽  
Polymer Metal ◽  
Free Volume Hole

The Absolute Free Volume Fraction in Polymers from the Positron Lifetime Measurements

2001 ◽  
Vol 363-365 ◽  
pp. 269-271 ◽  
Author(s):  
Jozef Krištiak ◽  
P. Bandžuch ◽  
O. Šauša ◽  
J. Zrubcová ◽  
Josef Bartoš
Keyword(s):  
Free Volume ◽  
Positron Lifetime ◽  
Volume Fraction ◽  
Lifetime Measurements ◽  
Free Volume Fraction ◽  
The Absolute

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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