Positron Annihilation Lifetime Spectroscopy Applied to the Measurement of Hole Volumes in Crosslinking Polyimides

Baugher, A. H.; Kossler, W. J.; Petzinger, K. G.; Pater, Ruth H.

doi:10.4028/www.scientific.net/msf.255-257.57

Cited by 10 publications

(8 citation statements)

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“…It is frequently used to determine the size distribution of free volume holes in polymers [7,8]. All of these measurements are based on the interaction of the free volume holes and the so-called ortho-positronium atom.…”

Section: Introductionmentioning

confidence: 99%

Tracking of the physical ageing of amorphous pharmaceutical polymeric excipients by positron annihilation spectroscopy

Zelkó

Orbán

Süvegh

2006

Journal of Pharmaceutical and Biomedical Analysis

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Section: Introductionmentioning

confidence: 99%

Tracking of the physical ageing of amorphous pharmaceutical polymeric excipients by positron annihilation spectroscopy

Zelkó

Orbán

Süvegh

2006

Journal of Pharmaceutical and Biomedical Analysis

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“…Ps is formed in small local free volumes (holes) that form the (excess) free volume in amorphous polymers, or, if formed elsewhere (in the interstitial free volume), trapped by these holes (Anderson localisation [27] ) after a diffusion over a mean path of $1 nm. [28] Due to annihilation of o-Ps with an electron other than its bound partner, and with opposite spin, during a collision with a molecule in the hole wall the o-Ps lifetime reduces from its value in a vacuum, 142 ns (self annihilation), to the low ns-range (pick-off annihilation, po).…”

Section: Introductionmentioning

confidence: 99%

The Structure of the Free Volume in Poly(styrene‐co‐acrylonitrile) from Positron Lifetime and Pressure Volume Temperature (PVT) Experiments

Dlubek

Бондаренко

Al-Qaradawi

et al. 2004

Macro Chemistry & Physics

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Summary: The structure of the free volume and its temperature dependence between 25 and 190 °C of copolymers of styrene with acrylonitrile, SAN (0 to 50 mol‐% AN), is studied by pressure volume temperature (PVT) experiments and positron annihilation lifetime spectroscopy (PALS). In this second part of the work, PALS data are reported from which the temperature dependence of the mean size and size distribution of local free volumes (subnanometer size holes) is analysed. The mean hole volume, vh, varies in PS between 105 Å3 (27 °C) and 220 Å3 (190 °C), and shows a systematic decrease with increasing AN content, at Tg from 121 Å3 for PS to 102 (±2) Å3 for SAN50. The specific number of holes, $N_{\rm h} '$, estimated from a comparison of PVT and PALS results, is independent on the temperature and the composition of SAN, $N_{\rm h} '$ = (0.56 ± 0.02) × 1021 g−1 which corresponds to Nh(Tg) = $N_{\rm h} '$/V(Tg) = 0.59 nm−3 and 1/Nh(Tg) = 1.7 nm3 for the volume which contains one hole. The analysed size distributions of the holes above Tg follow the compressibility of the free volume as it is predicted by the theory of thermal volume fluctuation. Moreover, we showed that the bulk elasticity modulus follows mastercurves as a function of vh above and below Tg.Free volume hole radius distribution n(rh) in PS for three different temperatures.magnified imageFree volume hole radius distribution n(rh) in PS for three different temperatures.

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“…It is frequently used to determine the size distribution of free volume holes in polymers. [13][14][15] All of these measurements are based on the interaction of the free volume holes and the so-called orthopositronium atom. 16 When positrons are injected to an amorphous molecular material, they form three different states in the simplest case.…”

Section: Introductionmentioning

confidence: 99%

Physical Aging of Poly(vinylpyrrolidone) under Different Humidity Conditions

Süvegh

Zelkó

2002

Macromolecules

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The physical aging of poly(vinylpyrrolidone) (PVP K25) was studied under different storage conditions by positron lifetime spectroscopy and scanning electron microscopy. The transition from the glassy state (at RT and 55% RH) to the completely plasticized wet rubbery state (at RT and 75% RH) is not continuous in PVP K25. It was found that not only the actual water content of the material but also its storage history determines the size distribution of free volume holes in it. At 65% RH a slow anomalous structure formation was observed. By the means of ab initio calculations on simplified model molecules, it was determined that polymer chains and water molecules are able to form a hydrogen bound "network" under certain humidity conditions.

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Positron Annihilation Lifetime Spectroscopy Applied to the Measurement of Hole Volumes in Crosslinking Polyimides

Cited by 10 publications

References 0 publications

Tracking of the physical ageing of amorphous pharmaceutical polymeric excipients by positron annihilation spectroscopy

Tracking of the physical ageing of amorphous pharmaceutical polymeric excipients by positron annihilation spectroscopy

The Structure of the Free Volume in Poly(styrene‐co‐acrylonitrile) from Positron Lifetime and Pressure Volume Temperature (PVT) Experiments

Physical Aging of Poly(vinylpyrrolidone) under Different Humidity Conditions

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