Positronium Lifetime in an Ellipsoidal Free-Volume Hole of Polymers

1994 ◽  
Vol 175-178 ◽  
pp. 691-694 ◽  
Author(s):  
Yan Ching Jean ◽  
Hong Shi ◽  
G.H. Dai ◽  
C.M. Huang ◽  
John Liu
Keyword(s):  
Free Volume ◽  
Positronium Lifetime ◽  
Free Volume Hole

scholarly journals Effect of Plasticization on Free-volume Hole of Epoxy Resin Evaluated by Positronium Lifetime.

RADIOISOTOPES ◽  
2002 ◽  
Vol 51 (2) ◽  
pp. 60-65
Author(s):  
Kenji ITO ◽  
Shingo HIRANO ◽  
Akira KISHIMOTO ◽  
Masaru MIYAYAMA ◽  
Yusuke UJIHIRA
Keyword(s):  
Epoxy Resin ◽  
Free Volume ◽  
Positronium Lifetime ◽  
Free Volume Hole

FREE VOLUME RELATED STRUCTURAL CHANGES IN THE EPOXY POLYMER TGDDM

1994 ◽  
Vol 08 (13) ◽  
pp. 1699-1711 ◽  
Author(s):  
V. RAVINDRACHARY ◽  
R. RAMANI ◽  
C. RANGANATHAIAH ◽  
S. GOPAL
Keyword(s):  
Free Volume ◽  
Structural Changes ◽  
Annealing Temperature ◽  
Epoxy Polymer ◽  
Slow Increase ◽  
Treatment Variation ◽  
Kinetic Relations ◽  
Long Lifetime ◽  
Average Size ◽  
Free Volume Hole

Positron lifetime measurements have been carried out in an amine-cured epoxy polymer TGDDM/DDS/BFE as a function of annealing temperature. The measured spectra are best fitted to three component analysis. From the measured long lifetime component the average size of the free volume holes has been calculated following Nakanishi et al.’s treatment. Variation of lifetime parameters with temperature indicates the preferential trapping of positronium atoms in the regions of increased free volume hole sizes. On the other hand, positrons are being trapped at micro-voids in the ordered regions. The slow increase of free volume upto 170°C may be due to the thermal expansion and we measure 170° C as the Tg for this epoxy. Lifetime data are also used to calculate the trapping rates in the ordered and disordered regions of the epoxy based on Goldanskii’s kinetic relations.

A Positron-Annihilation-Lifetime study of Polymer Blends

1993 ◽  
Vol 321 ◽  
Author(s):  
J. Liu ◽  
Y. C. Jean ◽  
H. Yang
Keyword(s):  
Bisphenol A ◽  
Polymer Blends ◽  
Positron Annihilation ◽  
Free Volume ◽  
Weight Fraction ◽  
Bisphenol A Polycarbonate ◽  
Positron Annihilation Lifetime ◽  
Miscible Blend ◽  
Immiscible Blend ◽  
Free Volume Hole

ABSTRACTPositron-annihilation-lifetime (PAL) spectroscopy has been utilized to investigate the free-volume properties of two types of polymer blends, a miscible blend of bisphenol-A polycarbonate (PC) and tetramethyl bisphenol-A polycarbonate (TMPC), and an immiscible blend of PC and polystyrene (PS). In the miscible blend, the free-volume hole size and its fraction follow a linear relationship with respect to the weight fraction while in the immiscible blend, the relationship is not linearly additive. The free-volume hole distributions in the immiscible blend are found to be significantly broader than those in the pure polymers. The difference is thought to be a result of the free volume formed and associated with the conformation and interchain packing between the dissimilar chains in incompatible polymers.

Pressure dependence of free-volume hole properties in an epoxy polymer

1992 ◽  
Vol 96 (1) ◽  
pp. 492-495 ◽  
Author(s):  
Q. Deng ◽  
C. S. Sundar ◽  
Y. C. Jean
Keyword(s):  
Free Volume ◽  
Pressure Dependence ◽  
Epoxy Polymer ◽  
Free Volume Hole

Positronium Lifetime Study on Subnanoscopic Structure of Polyrotaxane

2012 ◽  
Vol 733 ◽  
pp. 167-170
Author(s):  
K. Ito ◽  
Chang Ming Zhao ◽  
Kohzo Ito ◽  
Yoshinori Kobayashi
Keyword(s):  
Ethylene Glycol ◽  
Temperature Dependence ◽  
Positron Annihilation ◽  
Chemical Structure ◽  
Poly Ethylene Glycol ◽  
Positron Annihilation Lifetime ◽  
Positronium Lifetime ◽  
End Groups ◽  
Poly Ethylene ◽  
Free Volume Hole

The subnanoscopic structures of polyrotaxanes, prepared from α-cyclodextrins, poly(ethylene glycol), and bulky adamantane end groups, were examined by means of the positron annihilation lifetime technique, in consideration of the free-volume hole, quantified from the long-lived ortho-positronium (o-Ps) lifetimes. The influence of the chemical structure on the temperature dependence of the o-Ps lifetimes are discussed.

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