BS ISO 4652:2020 pdf free.Rubber compounding ingredients一Carbon black一 Determination of specific surface area by nitrogen adsorption methods一Single-point procedures.
BS ISO 4652 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.The mixed gas of helium and nitrogen (volume fraction 70 % and 30 %, respectively) is dosed to the degassed sample at the temperature of liquid nitrogen. The nitrogen in the mixed gas is adsorbed on the surface of a test portion of carbon black, so that the composition of the gas changes. The nitrogen is then desorbed by warming the test portion and the ratio of the mixed gas changes again. Since the thermal conductivity varies depending on the mixed gas concentration, it is possible to determine the amount of absorbed nitrogen gas using the thermal conductivity detector (TCD] of the system. Almost all the operations are automatically performed.Prepare a test portion by roughly weighing the mass of test portion given in Table 1. If the approximate specific surface area of the sample is not known, preliminary test may be carried out to determine the mass of the test portion. The final mass of the test portion to be used for the calculation is weighed and determined in 4.6.Z, 5.5.2.2 and 5.5.3.5 of each procedure.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. BS ISO 4652 pdf download.