Particle shape and orientation in laser diffraction and static image analysis size distribution analysis of micrometer sized rectangular particles

Abstract

A systematic study has been described on the laser diffraction (LD) and static image analysis (SIA) of rectangular particles [1]. To rule out powder sampling, sample dispersion and particle orientation as a possible root cause for differences in size distribution profile, powder samples were initially immobilized by means of a dry disperser onto a glass plate. For a defined region of the glass plate the diffraction pattern as induced by the dispersed particles, and the 2D dimensions of the individual particles were measured by LD and optical microscopy, respectively. Correlation between LD and SIA could be demonstrated considering the scattering intensity of the individual particles as the most dominating factor. For both spherical and rectangular particles, theory explains the latter to relate to the square of their projected area. In traditional LD, the size distribution profile is dominated by the maximum projected area of the particles (A), and the diffraction diameters of a rectangular particle with length L and breadth B are perceived by the LD instrument to correspond by approximation with spheres having a diameter of ∅ L and ∅ B , respectively. Weighting for differences in scattering intensity between spherical and Page 3 of 56 rectangular particles exlains each rectangular particle to contribute to the overall LD volume probability distribution proportional to A 2 /L and A 2 /B. Accordingly, for rectangular particles this scattering intensity weighted diffraction diameter (SIWDD) concept explains an overestimation of their shortest dimension and an underestimation of their longest dimension. For this study various samples have been analysed with the longest dimension of the particles ranging from ca. 10 to 1000 µm. For a variety of pharmaceutical powders all with a different rectangular particle size and shape, the demonstrated correlation between LD and SIA aims to facilitate the user in a better validation of LD methods based on SIA data.

Determination of particle size, surface area, and shape of supplementary cementitious materials by different techniques

“…Differences between PSD and SIA results are usually attributed to insufficient dispersion of the fine particles in the case of SIA, or inaccuracies in the optical model in the case of laser diffraction [29]. In this study, different optical models were used when analyzing the particle size of the slag via laser diffraction, and the results derived from this technique are three times smaller than the ones obtained applying SIA.…”

Aqueous colloids of graphene oxide nanosheets by exfoliation of graphite oxide without ultrasonication

“…However, the rates of increase of these two parameters are significantly reduced, from 22711·3 to 27·7% and from 150 to 2·4%. Since laser particle size measurement produces oversized size distribution and exaggerated distribution broadness for particles with large aspect ratio (Xu and Di Guida 2003;Tinke et al 2008), the increasing mean size and broadening distribution may be ascribed to the exfoliation of graphite oxide into graphite oxide nanosheets with one or more layers. The obvious reduction in increased rates of mean size and distribution presumably suggests that the exfoliation level of graphite oxide particles reaches a maximum in 2-Day period after 48 h treatment of magnetic stirring and heating.…”

Modeling and comparative analysis of packing of the polyfractional mixture of B4C powder

“…Basically the real shape of the powder particles is idealized in a model by elemental bodies (usually by spheres) [1]. As a result of particle packing modeling, with satisfactory accuracy, imitating the microstructure, the task adds up to the search of the value of model input parameters responsible for the characteristics of grain-size composition [2,3].…”