Free-volume and pore size distributions determined by numerical Laplace inversion of positron annihilation lifetime data

Gregory, Roger B.

doi:10.1063/1.349057

Cited by 146 publications

(92 citation statements)

References 19 publications

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“…Our results suggest that there is a change in the free-volume distribution at yielding. Positron annihilation lifetime spectroscopy (PALS) is a powerful method for obtaining information related to the free volume [25]. Although it is difficult to obtain the size of strongly anisotropic cavities, as shown in Fig.…”

Section: Discussionmentioning

confidence: 99%

Persistent homology analysis of craze formation

2017

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We apply a persistent homology analysis to investigate the behavior of nanovoids during the crazing process of glassy polymers. We carry out a coarse-grained molecular dynamics simulation of the uniaxial deformation of an amorphous polymer and analyze the results with persistent homology. Persistent homology reveals the void coalescence during craze formation, and the results suggest that the yielding process is regarded as the percolation of nanovoids created by deformation.

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Section: Discussionmentioning

confidence: 99%

Persistent homology analysis of craze formation

2017

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“…On the other hand, analysis in terms of a distribution of o-Ps lifetimes allows one to get the volume distribution function of the nanoholes [2]. In a recent paper [3] we showed the superiority of the latter model with respect to that one where each positron state decays with a single time constant; in the present work we compare the results supplied by two algorithms able to give lifetime distributions, that is, MELT [4] and LT [5].…”

Section: Introductionmentioning

confidence: 92%

Discrete and Continuous Analysis of Positron Lifetime Spectra: a Comparison

Consolati

Quasso

1999

Acta Phys. Pol. A

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Positron lifetime spectra in poly [1-(trimethylsilyl)]propine membranes were collected at different temperatures and various number of accumulated counts, in order to compare the results from analyses obtained by different decay models: discrete (that is, purely exponential) or continuous (with at least one distribution of lifetimes). Analysis into four discrete components is inadequate, unless a low number of counts (1 to 2 millions) is accumulated. Conversely, deconvolutions which allow the ortho-positronium lifetime to be distributed give satisfactory fits, even at the highest statistics (60 millions). An equivalent good fit in terms of x 2 test is obtained with a five discrete components analysis, from which it is possible to extract information on the first moments (centroid and standard deviation) of ortho-positronium lifetime distribution.

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“…39 Transformation from annihilation rate probability density function (PDF) into the corresponding free volume radius PDF and free volume size PDF were accomplished by the method of Gregory. 49,50 The expressions used to obtain free volume radius PDF and free volume size PDF are…”

Section: Positron Annihilation Lifetime Measurementsmentioning

confidence: 99%

A new insight into interface widths in binary polymer blends based on ortho‐positronium lifetime studies

Ramya

Ranganathaiah

2012

J of Applied Polymer Sci

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The interface widths in two immiscible polymer blend (Poly vinyl chloride (PVC)/Polystyrene (PS)) and PVC/Ethylene Vinyl Acetate (EVA) are determined experimentally using hydrodynamic interaction approach through free volume measurement by positron annihilation lifetime spectroscopy. For comparison, the same study is performed in a miscible blend (Styrene Acrylonitrile (SAN)/Poly Methyl Methacrylate (PMMA)). The interfacial width (Dl) is evaluated from the hydrodynamic interaction (a) based on Kirkwood-Risemann theory and friction coefficient from Stokes equation. Friction at the interface of a binary blend evidences how close the surfaces of the polymer chains come or stay apart which in turn depends on the type of force/interaction at the interface. In this work, we define interface width from a different perspective of Flory-Huggins interaction approach. Measured composition dependent interface widths in the three blends studied clearly demonstrate the sensitivity of the present method. In miscible blend, high friction at the interface results in stronger hydrodynamic interaction and hence smaller interface widths (0.36-1.97 Å ), whereas weak or no interaction in immiscible blends produce wider widths (2.81-25.0 Å ).

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Free-volume and pore size distributions determined by numerical Laplace inversion of positron annihilation lifetime data

Cited by 146 publications

References 19 publications

Persistent homology analysis of craze formation

Persistent homology analysis of craze formation

Discrete and Continuous Analysis of Positron Lifetime Spectra: a Comparison

A new insight into interface widths in binary polymer blends based on ortho‐positronium lifetime studies

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