GB/T 3780.5-2017Carbon black - Part5: Determination of specific surface area - CTAB test method (English PDF)

5.1 Buffer solution, pH=7, dissolve 2.722g of potassium dihydrogen phosphate

(KH2PO4), 4.260g of disodium hydrogen phosphate (Na 2HPO4) and 1.169g of sodium chloride (NaCl) into 1dm

3 of water.

5.2 CTAB solution, c(C19H42BrN) = 0.01mol/L; take 3.64g of CTAB

(cetyltrimethylammonium bromide) to dissolve into 900cm

3 of water; add 100cm

3 of buffer solution; heat to 27°C~37°C and dissolve; cool off to 23°C~25°C before use. If the room temperature is lower than 23°C, it may cause the CTAB to slowly crystalize.

5.3

OT (sodium sulfosuccinate dioctyl ester) solution, c(C20H37NaO7S) = 0.0022mol/L;

take 1.000g of 100% OT into 1dm

3 of water containing 2.5cm

3 of formaldehyde solution (mass fraction of 37%); use magnetic stirrer to vigorously stir for 48h; after tightening the lid, place into a cool and dry place for 12d then it can be used. The unsealed OT reagent shall be stored in a desiccator. OT solution is prone to degradation and its concentration change shall be noted during the use period.

5.4 Emulsifier OP (octyl phenyl polyoxyethylene ether, Triton × -100) solution, mass

fraction of 0.015%; completely dissolve 0.15g of OP in 1dm

3 of water with a magnetic stirrer.

5.5 Industry tint reference black (ITRB with specific surface area of 83.0×103m

2

/kg) or industry reference carbon black 4# (IRC 4# with specific surface area of

78.5×103m

2

/kg), and conform to GB/T 9578.

b) Plug the stopper after adding the magnetic stirring bar; place into the ultrasonic electromagnetic disperser; soaking depth shall be at least 50mm; keep the water bath temperature at 23°C~25°C; sonicate in the water bath for 1min; then stir for

1min; repeat the operation for twice; the total time is 6min.

8.4

Place the dry filter membrane into the sample filter cartridge; install it according to the installation requirements of filter cartridge of the pressured filtration device.

8.5

Dry the water droplets outside the conical flask; thoroughly pour the mixture of carbon black sample and CTAB solution into the sample filter cartridge; tighten the upper lid; install on the pressure filtration device; turn on the compressed gas; adjust he gas pressure to 0.4MPa ~ 0.7MPa; it is better to filter out the liquid into a quick drop.

Discard the initially discharged about 10cm

3 filtrate; COLLECT all the filtrate flowing out before the foam at the lower end outlet of the sample filter cartridge is formed INTO

50cm

3 conical flask; plug the stopper, shake for testing. If the filtrate of carbon black is diafiltered, the sample shall be discarded, and can’t be re-filtered.

8.6 Install and debug the carbon black specific surface area tester or potentiometric

titrator according to the instrument manual; drain all bubbles on the pipeline and interfaces of the titrator.

8.7 TRANSFER 5cm

3 of filtrate from the to-be-tested filtrate in the 50cm

3 conical flask

INTO a clean quartz cup; after adding 15cm

3 of OP solution and magnetic stirring bar, place the quartz cup into the instrument measuring tank (hand can’t touch the transparent surface of the quartz cup). Press the “Titration” button; the titration shall start automatically and the titration volume (cm

3

) shall be shown on the digital display at the same time; after it stops automatically, record the consumed volume of OT solution, V; accurate to 0.01cm

3

.

9.3 Draw a standard curve with OT solution consumption volume Vi (cm

3

) as the ordinate, sample mass mi (g) as the abscissa; calculate the slope b (cm

3

/g) and the intercept V0 (cm

3

) by the least squares; obtain the regression equation. Calculate the specific surface area as per the Formula (1) in 11.1; the difference between the calculated result and the standard value shall be no more than 1.5×10

3 m

2

/g; otherwise, repeat the steps from 9.1 to 9.3.

average value; then perform the data rounding-off as per the report requirements or the provisions of GB/T 3778 through the GB/T 8170.

12.1 Repeatability – the absolute difference between two independent test results

obtained under the repeatability conditions shall be no greater than 1.9% of its average value.

12.2 Reproducibility – the absolute difference between two independent test results

obtained under the reproducibility conditions shall be no greater than 5.1% of its average value.