Positron Annihilation Study on Nickel and Iron Nano-Particles in Natural Rubber Composites

Aly, Emad H.

doi:10.3844/ajassp.2011.147.155

Cited by 15 publications

(1 citation statement)

References 31 publications

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“…Complex and interesting features concern the free volume in the polymeric matrix of the nanocomposite. In fact, while various investigations have shown a decrease in the free volume when the matrix incorporates the nanoparticles (e.g., [ 85 , 86 , 87 , 88 ]), in other studies [ 89 , 90 , 91 ], the free volume increases with the concentration of nanofiller, which has been correlated to a weak interaction between the matrix and the filler, favoring the creation of large free volume holes. On the other hand, an interfacial interaction between polymer matrix and nanofiller sufficiently strong to prevail on the interactions among nanoparticles improves the dispersion of nanofiller in the matrix, with a consequent reduction of 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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Microstructural characterization of short glass fibre reinforced polyethersulfone composites

Munirathnamma

Ravikumar

2016

J of Applied Polymer Sci

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Effect of TiO₂ nano‐filler on the electrical conductivity and free volume parameters of PSAN/TiO₂ nanocomposites

Ningaraju

Ravikumar

2016

Polymer Composites

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To explore the effect of filler on the electrical conductivity of polymer nanocomposites, polystyrene coacrylonitrile and TiO 2 (PSAN/TiO 2 ) nanocomposites of different TiO 2 wt% have been prepared. The microstructural characterization has been performed by positron annihilation lifetime spectroscopy (PALS). Positron lifetime parameters viz. o-Ps lifetime (s 3 ) and free volume size (V f ) decreases up to 0.6 wt% suggests the filling of the cavities by Ti 31 and O 2 ions as well as complex formation. The increased free volume size (V f ) after 0.6 wt% of TiO 2 was attributed to the o-Ps annihilation at the interface of PSAN and TiO 2 nanoclusters. The variation of electrical conductivity at lower and higher concentration of TiO 2 is attributed to the blocking effect and space charge effect, respectively. The electrical conductivity decreases along with the free volume sizes at lower concentration of TiO 2 due to the hindrance of the ions mobility. The increased conductivity with the increased free volume sizes indicates the formation of more void space at the interface due to the formation of TiO 2 nanoclusters. The surface morphology of the nanocomposites studied by scanning electron microscopy (SEM) shows uniform dispersion at the lower wt% of TiO 2 and increased size of nanocluster formation at the higher concentration of TiO 2 nanoparticles in PSAN matrix. The crystallinity evaluated by X-ray diffraction (XRD) results also indicates the formation of TiO 2 nanoclusters between 0.6 and 1.0 wt% of TiO 2 . Fourier transform infrared spectroscopy (FTIR) suggests the improved chemical and physical interaction between the functional groups of TiO 2 and polymer side chain. POLYM. COMPOS., 00:000-000,

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Positron Annihilation Study on Nickel and Iron Nano-Particles in Natural Rubber Composites

Cited by 15 publications

References 31 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

Microstructural characterization of short glass fibre reinforced polyethersulfone composites

Effect of TiO₂ nano‐filler on the electrical conductivity and free volume parameters of PSAN/TiO₂ nanocomposites

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Positron Annihilation Study on Nickel and Iron Nano-Particles in Natural Rubber Composites

Cited by 15 publications

References 31 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

Microstructural characterization of short glass fibre reinforced polyethersulfone composites

Effect of TiO2 nano‐filler on the electrical conductivity and free volume parameters of PSAN/TiO2 nanocomposites

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Product

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Effect of TiO₂ nano‐filler on the electrical conductivity and free volume parameters of PSAN/TiO₂ nanocomposites