ISO 13317-1:2024 重力液体沈降法による粒度分布の測定 | ページ 6

3.1

sedimentation

directional motion of particles (3.7) in a viscous liquid under the action of gravity or centrifugal fields

Note 1 to entry: For a positive density contrast (3.17) , sedimentation occurs in the direction of gravitational acceleration; it is counter directed to this acceleration for a negative density contrast.

Note 2 to entry: A downward motion under gravity is also called"settling" or"falling".

Note 3 to entry: An upward motion under gravity is also called"creaming" (e.g. droplets) or more generally,"rising" or"floating".

3.2

migration

directional motion of particles (3.7) in a viscous liquid under the action of a force field

Note 1 to entry: Migration in gravitational or centrifugal fields is called sedimentation (3.1) .

3.3

terminal sedimentation velocity

sedimentation (3.1) velocity in the case that gravity or centrifugal force is completely balanced by buoyancy and drag force

3.4

Stokes diameter

equivalent diameter of a sphere that has the same buoyant density (3.16) and terminal sedimentation velocity (3.3) as the real particle (3.7) in the same liquid under creeping flow (3.19) conditions

Note 1 to entry: The general rule that the buoyant density is used for calculating the Stokes diameter applies also to coated particles or multiconstituent particles (such as droplets in multiple emulsions). The buoyant density can be approximated with the skeleton density (3.14) for monoconstituent particles.

Note 2 to entry: For porous particles, it is common use to compute particle size based on the apparent particle density (3.15) . This approach considers the stagnant liquid in the open pores (3.9) as intrinsic constituent of the dispersed phase. Thus, the obtained size values are hydrodynamic equivalent diameters.

Note 3 to entry: For close-packed agglomerates (3.8) or aggregates, the buoyant density can be replaced by the apparent particle density – with particle referring to the agglomerate or aggregate – in order to get the hydrodynamic equivalent diameter.

3.5

shape correction factor

ratio of the sedimentation (3.1) velocity of a non-spherical particle (3.7) to the one of a spherical particle of the same volume and apparent particle density (3.15)

3.6

hindrance function

ratio of the terminal sedimentation velocity (3.3) of a particle (3.7) placed in a well-mixed dispersion divided by its sedimentation velocity in an infinite vessel for the absence of other particles

3.7

particle

minute piece of matter with defined physical boundaries

[SOURCE:ISO 26824:2022, 3.1.1, modified — Notes 1, 2 and 3 to entry have been deleted.]

3.8

agglomerate

cluster of particles (3.7) held together by weak or medium strong forces with an external surface area, which is similar to the sum of the surface areas of the individual particles

Note 1 to entry: The forces acting between the constituent particles of an agglomerate are relatively weak. They result, for example, from van der Waals attraction or simple physical entanglement.

Note 2 to entry: Agglomerates are also termed secondary particles and the original source particles are termed primary particles.

3.9

open pore

pore not totally enclosed by its walls and open to the surface either directly or by interconnecting with other pores and therefore accessible to liquid

[SOURCE:ISO 15901‑1:2016, 3.11, modified —"fluid" has been replaced with"liquid" in the definition.]

3.10

closed pore

pore totally enclosed by its walls and hence not interconnecting with other pores and not accessible to liquids

[SOURCE:ISO 15901‑1:2016, 3.10, modified —"fluids" has been replaced with"liquids" in the definition.]

3.11

dynamic viscosity

measure of flow resistance for Newtonian liquids calculated as the ratio of the shear stress to the rate of shear for laminar flow exposed to a pre-set shear stress or strain

3.12

apparent viscosity

measure of flow resistance for non-Newtonian liquids at a defined shear stress or strain calculated as the ratio of the shear stress to the shear rate

3.13

true density of the dispersed phase

ratio of mass to volume for a body solely consisting of the dispersed phase without pores, voids, inclusions or surface fissures

3.14

skeleton density

ratio of the sample mass and the volume of the sample including the volume of closed pores (if present) but excluding the volume of open pores (3.9)

Note 1 to entry: The skeleton density refers to solid particles (3.7) and is determined for samples of dry powder.

[SOURCE:ISO 12154:2014, 3.3, modified —"as well as that of void spaces between particles within the bulk sample" has been deleted from the definition and Note 1 to entry has been added.]

3.15

apparent particle density

effective particle density

ratio of mass to volume for a particle (3.7) including particulate inclusions, entrapped stagnant liquid and gas in pores, voids and surface fissures as well as surfaces layers and coatings

Note 1 to entry: The apparent particle density is the density of a migrating entity and is calculated as the weighted average of its constituents.

Note 2 to entry: The apparent particle density depends on the wettability of open pores (3.9) and the kinetics of wetting or replacement of pore liquid. Therefore, it is affected by sample preparation.

Note 3 to entry: The apparent particle density is not identical with the buoyant density (3.16) . They deviate from each other for porous particles and particle agglomerates (3.8) in particular.

3.16

buoyant density

ratio of mass to volume for a particle (3.7) including particulate inclusions, liquid and gas in closed pores and voids as well as surface layers and coatings, but excluding the liquid continuous phase that penetrates open pores (3.9)

Note 1 to entry: The buoyant density equals the (hypothetical) density of the continuous phase for which the gravitational force acting on the immersed particle is counterbalanced by buoyancy.

Note 2 to entry: The buoyant density of a particle can be experimentally determined (see ISO 18747-1 and ISO 18747-2 for more information).

Note 3 to entry: The buoyant density of monoconstituent particles can be approximated with their skeleton density (3.14) .

Note 4 to entry: The buoyant density of multiconstituent particles (e.g. coated pigments and droplets of multiple emulsions) can be approximated with the averaged densities of the single constituents.

Note 5 to entry: The buoyant density is affected by the adsorption of dissolved species at the particle surface and therefore depends on the solvent and its composition.

Note 6 to entry: The buoyant density is not identical with the apparent particle density (3.15) , particularly for porous particles and particle agglomerates (3.8) .

3.17

density contrast

difference between the particle (3.7) density and the density of the continuous phase

Note 1 to entry: For quantifying the density contrast, the buoyant (particle) density (3.16) is used, but for porous particles, the apparent particle density (3.15) is more appropriate.

3.18

particle Reynolds number

dimensionless parameter expressing the ratio of inertial to viscous forces within a fluid flowing past a particle (3.7)

Note 1 to entry: The particle Reynolds number is based on the volume equivalent diameter.

Note 2 to entry: In other contexts, the definition of the particle Reynolds number can refer to different equivalent diameters or to the equivalent radii.

Note 3 to entry: The particle Reynolds number is a characteristic of the flow field and mobility of the particle.

3.19

creeping flow

type of flow solely governed by viscous forces and not affected by inertial effects

Note 1 to entry: For moving particles (3.7) or for the flow past a particle, the creeping flow condition applies if the particle Reynolds number (3.18) is well below 0,25.

3.20

Brownian motion

random motion of particles (3.7) caused by collisions with the molecules or atoms of the surrounding continuous phase

Note 1 to entry: The trajectory of Brownian motion is not differentiable.

Note 2 to entry: Brownian motion results on a macroscopic level in mass transport of the dispersed phase, e.g. in case of diffusion, thermophoresis or photophoresis.

3.21

lower size limit

size of the smallest particles that are detectable and with a diffusional particle flux that is negligible compared to the sedimentational particle flux

Note 1 to entry: The ratio of sedimentational flux to diffusional flux (also called Péclet number, Pe) should be >1.

3.22

upper size limit

size of the largest particle (3.7) that satisfies the condition of creeping flow (3.19) and of which the terminal sedimentation velocity (3.3) is detectable

3.23

type of quantity

specification of the physical property employed to quantify the individual particle (3.7) fractions

Note 1 to entry: The type of quantity is a cumulable property of single particles or disperse systems, such as number, mass, intensity of scattered light (within the single scattering limit), light extinction (within the Lambert-Beer limit), refractive index increment or X-ray attenuation.

Note 2 to entry: The type of quantity is indicated by a numerical or character subscript when symbolising the density and cumulative function of a size distribution. Moreover, the subscript also specifies distribution parameters, such as median, mean and modal values or any quantiles.

3.24

sensitivity

change of instrument response with respect to changes in concentration or absolute quantity of particles (3.7) in a specified size class

Note 1 to entry: A concentration or quantity can be given in relative or absolute values depending on the detection aim.

Note 2 to entry: Sensitivity depends on the type of quantity (3.23) .

Note 3 to entry: Sensitivity is a function of size.

3.25

limit of quantity detection

smallest quantity of specified particle (3.7) size class, for which the instrument response can be distinguished from the background

Note 1 to entry: The limit of quantity detection depends on factors such as size range, precision, noise level and smoothing algorithms.

Note 2 to entry: The limit of quantity detection affects the lower size limit (3.21) and upper size limit (3.22) .

3.26

measurement uncertainty

uncertainty of measurement

parameter associated with the result of a measurement that characterises the dispersion of the values that can reasonably be attributed to the measurand

[SOURCE:ISO/IEC Guide 98-3:2008, 2.2.3, modified — the term"measurement uncertainty" has been added.]