BS ISO 4652:2020 pdf download.Rubber compounding ingredients — Carbon black — Determination of specific surface area by nitrogen adsorption methods — Single-point procedures.
1 Scope
This document specifies two methods for the determination of the specific surface area of types and grades of carbon black for use in the rubber industry:
— method A: automatic gas chromatography method (carrier gas method);
— method B: automatic volumetric method.
Somewhat different results might be obtained from the two methods. The degassing procedure differs between method A and method B, and it is important to investigate the possibility of correcting the results by using standard reference blacks.
The results might also differ from those obtained using the multipoint method specified in ISO 18852, which is the preferred method.
These methods are not applicable to porous carbon blacks.
2 Normative references
There are no normative references in this document.
3 Terms and definitions
No terms and definitions are listed in this document.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https://www.iso.org/obp
— IEC Electropedia: available at http://www.electropedia.org/
4.2.5 Pipe cleaner.
4.3 Reagents
4.3.1 Helium-nitrogen mixed gas.
The volume mixing ratio of helium and nitrogen is 7:3, and it is kept in a pressure vessel.
4.3.2 Nitrogen gas, of purity greater than 99,999 5 %.
4.3.3 Standard reference black.
4.4 Preparation of the sample portion
Pellets of carbon black may not be crushed. Unagitated, unpelletized carbon black may be
densified if desired.
4.6 Measurement procedure
4.6.1 After setting the degassed sample tube to the measurement unit and distributing helium-
nitrogen mixture gas (4.3.1), ensure that the baseline of the thermal conductivity detector is stable. Set
the baseline to zero.
4.6.2 After circulating helium-nitrogen mixture gas for a few minutes, the thermal conductivity
detector is turned on.
4.6.3 Cool the sample tube with the sample in the liquid nitrogen in the Dewar flask.
4.6.4 The baseline of the thermal conductivity detector becomes stable when the adsorption has been completed. Remove the sample tube out of the liquid nitrogen and warm it with the air blower to the room temperature.
To operate efficiently, degassing of the next sample portion may be done in parallel with the adsorption and desorption process.
4.6.5 The peak area of the desorption is stored in the device or in the control computer.
4.6.6 Calibrate the thermal conductivity detector for the next portion.
4.10 Test report
The test report shall include the following information:
a) all details necessary for complete identification of the sample;
b) a reference to this document including its year of publication, i.e. ISO 4652:2020;
c) the method used, i.e. method A;
d) the test results (corrected value if corrected), in m 2 /g;
e) the correction factor and standard reference black used, if applicable;
f) the date of the test.BS ISO 4652 pdf download.