Investigation of cation-exchanged montmorillonites by combined x-ray diffraction and positron annihilation lifetime spectroscopy

Abstract

A characterization of some mineral and organophilic montmorillonites has been carried out using x-ray diffraction and positron annihilation lifetime spectroscopy. The combination of the two techniques supplies information on the microscopic structure of clays, in particular on the fraction of interlayer gap which is occupied by water molecules in the mineral clays. Nanocavities among cations of quaternary ammonium salts inserted in the organophilic clays were also investigated and compared with those existing in the free salt.

Influence of MMT content on the microstructure and miscibility for PU/EP IPN nanocomposites by positron

“…In terms of the values reported by Consolati and Wang [8,9], the 2 N I can be calculated approximately as shown in Fig. 5.…”

“…The variation of I 2 is related to the interfacial interaction in the nanocomposites. Supposing there is no interfacial interaction between MMT and matrix, according to the simple mixture rule, it only comes from positron annihilation in MMT and matrix, I 2 should be linearly additive basis on the weight fraction [9], and we have:…”

Morphology of Free‐Volume Holes in Amorphous Polymers by Means of Positron Annihilation Lifetime Spectroscopy

“…(10.9) when m → ∞. Prisms and layered cavities have been used, for example, in structural studies of clays [Joshi et al, 1998;Consolati et al, 2002]. A discussion of pore-size distributions in low-dielectric thin films [Gidley et al, 2000] was based on cubic structures.…”

Positronium trapping in small voids: Influence of their shape on positron annihilation results

“…Cuboid and layered structures were used in structural studies of clays. 15,16 Discussion of pore size distributions in low dielectric thin films 17 was based on cubic structures. Of course, many other geometries are possible: for instance, ellipsoid holes were also considered 18 in an interesting attempt to frame free volumeholes in stretched semicrystalline polymers.…”