ISO 15825 pdf download Rubber compounding ingredients — Carbon black — Determination of aggregate size distribution by disc centrifuge photosedimentometry
This document specifies a method for determining the size distribution of carbon black aggregates,using a disc centrifuge photosedimentometer.This technique is based on the hydrodynamic behaviourof carbon black in a centrifugal field.The determination of the aggregate size distribution is importantin the evaluation of carbon black used in the rubber industry.
The following documents are referred to in the text in such a way that some or all of their contentconstitutes requirements of this document. For dated references,only the edition cited applies.Forundated references, the latest edition of the referenced document (including any amendments) applies.IS0 1124, Rubber compounding ingredients —Carbon black shipment sampling procedures
ISO 3696,Water for analytical laboratory use — Specification and test methods
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:一IEC Electropedia: available at http://www.electropedia.org/
– ISO online browsing platform: available at http://www.iso.org/obp3.1 General terms
carbon black aggregate
discrete, rigid colloidal entity that is the smallest dispersible unit in a suspensionNote 1 to entry: It is composed of extensively coalesced particles.
inert liquid injected into the disc prior to the sample, through which aggregates sedimentNote 1 to entry: Alkaline conditions minimize agglomeration of dispersed aggregates in most cases.3.1.3
liquid in which aggregates are dispersed
mathematical description of the sedimentation of a spherical particle:
D st is the Stokes diameter (nm);
η is the viscosity of the spin fluid (Pa·s);
R is the distance of the photodetector from the centre of rotation (cm);
S is the distance of the air-liquid interface from the centre of rotation (cm);
t is the time of centrifugation (s);
ρ 1 is the density of the carbon black (Mg/m 3 );
ρ 2 is the density of the spin fluid (Mg/m 3 );
ω is the rotational velocity (rad/s).
density of the aggregate in Mg/m 3
Note 1 to entry: For carbon black, 1,86 × 10 3 kg/m 3 (1,86 g/cm 3 ) is used as a typical value.
3.2 Terms concerning aggregate dimensions
diameter of a sphere which sediments in a viscous medium in a centrifugal or gravitational field according to the Stokes equation Note 1 to entry: A non-spherical object, such as a carbon black aggregate, may also be represented in terms of an equivalent Stokes diameter if it is considered as behaving as a smooth, rigid sphere of the same density and with the same sedimentation rate as the object.
Note 2 to entry: For carbon black, Stokes diameter is expressed in nanometres (nm).
average diameter calculated from the differential mass distribution curve
Note 1 to entry: It represents the first moment of the differential distribution.
Note 2 to entry: In the software of the Brookhaven disc centrifuge the mass distribution is called “Volume (Mass)”and mean diameter is reported as “Mean”.
Note 3 to entry: D mean is used for reporting purposes only.
x-value of the point on the mass distribution curve at which 50 % by mass of the test sample is largerand 50 % by mass of the test sample is smaller
Note 1 to entry: It represents the median value of the distribution.
Note 2 to entry: In the software of the Brookhaven disc centrifuge the median Stokes diameter is reported as “d50”.Note 3 to entry: D5o is used for reporting purposes only.
value at which the most frequent diameter occurrence is observed, which is portrayed as a peak in thedistribution curve
Note 1 to entry: In some cases, there may be more than one mode indicated.Note 2 to entry: Dmode is used for reporting purposes only.
x-value of the point on the mass distribution curve at which 75 % of the sample is larger, and 25 %smaller3.2.6
x-value of the point on the mass distribution curve at which 75 % of the sample is smaller, and 25 % larger3.2.7
ratio of upper quartile to lower quartile
Note 1 to entry: In the software of the Brookhaven disc centrifuge the quartile ratio is reported as “d75/d25”.3.2.8
width of the plot of the mass distribution measured at the half-maximum point of the mode, which is ameasure of the breadth of the aggregate size distribution
Note 1 to entry: In the software of the Brookhaven disc centrifuge AD 50 is reported as”FWHM”M(full wiath athalf maximum).