Radiation induced nano-scale free volume modifications in amorphous polymeric material: a study using positron annihilation lifetime spectroscopy

Kumar, Rajesh; Singh, Paramjit; Gupta, Sanjeev Kumar; Gupta, Rashi; Jaiswal, Manoj Kumar; Prasad, Mahanth; Roychowdhury, Anirban; Chauhan, R. P.; Das, Dipankar

doi:10.1007/s10967-017-5510-9

Cited by 9 publications

(2 citation statements)

References 48 publications

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“…An investigation on the effect of gamma irradiation on CR-39 has been carried out by Kumar et al [ 111 ]. The goal was to study the microstructural changes involved by irradiation and in particular the free volume.…”

Section: Discussion Of Some Pals Results In Polymeric Systemsmentioning

confidence: 99%

Probing the Free Volume in Polymers by Means of Positron Annihilation Lifetime Spectroscopy

Consolati

Nichetti²,

Quasso

2023

Polymers

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Positron annihilation lifetime spectroscopy (PALS) is a valuable technique to investigate defects in solids, such as vacancy clusters and grain boundaries in metals and alloys, as well as lattice imperfections in semiconductors. Positron spectroscopy is able to reveal the size, structure and concentration of vacancies with a sensitivity of 10−7. In the field of porous and amorphous systems, PALS can probe cavities in the range from a few tenths up to several tens of nm. In the case of polymers, PALS is one of the few techniques able to give information on the holes forming the free volume. This quantity, which cannot be measured with macroscopic techniques, is correlated to important mechanical, thermal, and transport properties of polymers. It can be deduced theoretically by applying suitable equations of state derived by cell models, and PALS supplies a quantitative measure of the free volume by probing the corresponding sub-nanometric holes. The system used is positronium (Ps), an unstable atom formed by a positron and an electron, whose lifetime can be related to the typical size of the holes. When analyzed in terms of continuous lifetimes, the positron annihilation spectrum allows one to gain insight into the distribution of the free volume holes, an almost unique feature of this technique. The present paper is an overview of PALS, addressed in particular to readers not familiar with this technique, with emphasis on the experimental aspects. After a general introduction on free volume, positronium, and the experimental apparatus needed to acquire the corresponding lifetime, some of the recent results obtained by various groups will be shown, highlighting the connections between the free volume as probed by PALS and structural properties of the investigated materials.

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Section: Discussion Of Some Pals Results In Polymeric Systemsmentioning

confidence: 99%

Probing the Free Volume in Polymers by Means of Positron Annihilation Lifetime Spectroscopy

Consolati

Nichetti²,

Quasso

2023

Polymers

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“…In Table 2 , we report known experimental data on

and

of some other materials, which are organized in series that underwent different physical or chemical treatments, to study any modifications of the nanovoid structure. In particular, the DOP series corresponds to amorphous polycarbonate polymeric films (CR-39) samples exposed with gamma radiation [ 31 ]; the ZMS-5 series corresponds to calcinated zeolites [ 32 ]; the series signed Ag/polymer is Ag nanoparticles embedded in a polymer matrix [ 33 ]; the series

-As

is mechanochemical milled nanoarsenical pellets [ 34 ]; finally the last series corresponds to dimethacrylate composites after photopolymerization [ 35 ].…”

Section: Connection With Experimental Data On Annihilation Ratesmentioning

confidence: 99%

Positronium Confined in Nanocavities: The Role of Electron Exchange Correlations

2021

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Positronium atoms (Ps) are commonly employed as a probe to characterize nanometric or subnanometric voids or vacancies in nonmetallic materials, where Ps can end up confined. The annihilation lifetime of a trapped Ps is strongly modified by pickoff and depends on the cavity size and on the electron density in the confining cavity surface. Here, we develop a theory of the Ps annihilation in nanocavities based on the fundamental role of the exchange correlations between the Ps-electron and the outer electrons, which are not usually considered but must be considered to correctly theorize the pickoff annihilation processes. We obtain an important relation connecting the two relevant annihilation rates (for the p-Psand the o-Ps) with the electron density, which has the property of being totally independent of the geometrical characteristics of the nanoporous medium. This general relation can be used to gather information on the electron density and on the average cavity radius of the confining medium, starting from the experimental data on PALS annihilation spectra. Moreover, by analyzing our results, we also highlight that a reliable interpretation of the PALS spectra can only be obtained if the rule of 1/3 between the intensities of p-Psand o-Pslifetimes can be fulfilled.

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Gamma Radiation Effects on Recycled e‐PC

De la Colina Martínez,

Hernández,

Barrera

et al. 2023

Electronic Waste Management

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Radiation induced nano-scale free volume modifications in amorphous polymeric material: a study using positron annihilation lifetime spectroscopy

Cited by 9 publications

References 48 publications

Probing the Free Volume in Polymers by Means of Positron Annihilation Lifetime Spectroscopy

Probing the Free Volume in Polymers by Means of Positron Annihilation Lifetime Spectroscopy

Positronium Confined in Nanocavities: The Role of Electron Exchange Correlations

Gamma Radiation Effects on Recycled e‐PC

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