Author
M. Eldrup
Bio: M. Eldrup is an academic researcher. The author has contributed to research in topics: Vacancy defect & Positronium. The author has an hindex of 2, co-authored 3 publications receiving 1556 citations.
Papers
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TL;DR: In this article, the temperature dependence of positron lifetimes in both the brittle and plastic phases of trimethylacetic (pivalic) acid was examined using the positron lifetime technique.
1,640 citations
TL;DR: In this paper, the formation energy of the defects which trap ortho-positronium is estimated at E f v = 70 ± 10 kJ mol -1 (0.73 ± 0.1 eV).
30 citations
01 Jan 1981
TL;DR: The use of the positron annihilation technique (PAT) in the investigation of vacancies and phase transformations in molecular crystals is discussed in this paper, where it is shown that PET can be used to detect phase transformations.
Abstract: The use of the positron annihilation technique (PAT) in the investigation of vacancies and phase transformations in molecular crystals is discussed.
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TL;DR: In this article, the temperature dependence of positron lifetimes in both the brittle and plastic phases of trimethylacetic (pivalic) acid was examined using the positron lifetime technique.
1,640 citations
919 citations
TL;DR: In this paper, a review of microporous materials with a particular emphasis on amorphous polymers that possess intrinsic microporosity (IM), which is defined as microporeosity that arises directly from the shape and rigidity of component macromolecules.
Abstract: The past decade has seen the development of microporous materials (i.e., materials containing pores of dimensions <2 nm) derived wholly from organic components. Here we review this nascent area with a particular emphasis on amorphous polymers that possess intrinsic microporosity (IM), which is defined as microporosity that arises directly from the shape and rigidity of component macromolecules. Although IM can be readily identified within soluble non-network polymers and oligomers, for network polymers it is harder to differentiate IM from template effects that are responsible for the microporosity within hyper-cross-linked networks. The numerous examples of microporous polymers assembled from rigid monomers by the formation of rigid linking groups are surveyed and their IM assessed. The potential applications of these materials are highlighted.
704 citations
TL;DR: Positron annihilation spectroscopy for chemical analysis (PASCA) has been developed to analyze the microstructure of polymers as discussed by the authors, where the positronium atom is trapped in the atomic-scale holes which have a size ranging from 1 to 10 A. Theoretical aspects, experimental developments, and examples in analyzing the microstructures of epoxy, PEEK, and PMMA polymers are presented.
694 citations
TL;DR: In this paper, the authors synthesized ZIF-8 nanoparticles (size ∼ 60 nm and specific surface area ∼ 1300-1600 m2 g−1) were directly incorporated into a model polymer matrix (Matrimid® 5218) by solution mixing.
Abstract: As synthesised ZIF-8 nanoparticles (size ∼ 60 nm and specific surface area ∼ 1300–1600 m2 g−1) were directly incorporated into a model polymer matrix (Matrimid® 5218) by solution mixing. This produces flexible transparent membranes with excellent dispersion of nanoparticles (up to loadings of 30 wt%) with good adhesion within the polymer matrix, as confirmed by scanning electron microscopy, dynamic mechanical thermal analysis and gas sorption studies. Pure gas (H2, CO2, O2, N2 and CH4) permeation tests showed enhanced permeability of the mixed matrix membrane with negligible losses in selectivity. Positron annihilation lifetime spectroscopy (PALS) indicated that an increase in the free volume of the polymer with ZIF-8 loading together with the free diffusion of gas through the cages of ZIF-8 contributed to an increase in gas permeability of the composite membrane. The gas transport properties of the composite membranes were well predicted by a Maxwell model whilst the processing strategy reported can be extended to fabricate other polymer nanocomposite membranes intended for a wide range of emerging energy applications.
614 citations