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GB/T 3780 consists of the following parts under the general title Carbon black:
——Part 1: Test method for iodine adsorption number;
——Part 2: Determination of oil absorption number;
——Part 4: Determination of oil absorption number for compressed sample;
——Part 5: Determination of specific surface area—CTAB test method;
——Part 6: Determination of tinting strength;
——Part 7: Determination of pH value;
——Part 8: Determination of heating loss;
——Part 10: Determination of ash;
——Part 12: Inspection of impurity material;
——Part 14: Determination of sulfur content;
——Part 15: Determination of light transmittance of toluene extract;
——Part 17: Indirect determination of particle size—Reflectance method;
——Part 18: Standard test methods for evaluation in natural rubber (NR);
——Part 21: Determination of sieve residue—Water washing method;
——Part 22: Calculation of process indexes from an analysis of process control data;
——Part 23: Sampling and testing of carbon black fugitive emissions or other environmental particulate;
——Part 24: Determination of void volume.
This part is Part 2 of GB/T 3780.
This part is developed in accordance with the rules given in GB/T 1.1-2009.
This part replaces GB/T 3780.2-2007 Carbon black—Part 2: Determination of oil absorption number. In addition to editorial changes, the following main technical changes have been made with respect to GB/T 3780.2-2007:
——The contents of reagents and materials are added (see 5.1, 5.3);
——The precision of the microburet is modified (see 6.5 hereof; 11.1 of 2007 edition);
——“The oil absorption numbers of carbon black types listed in Table 1 are all read from the corresponding values at 70% of the maximum torque of the fitting curve” is added, which is more comprehensive and clearer (see 8.1.9);
——The requirements for oil density are added (see A.6 in Annex A);
——"Evaluation on mixing chamber of absorptometer” is added (see Annex E);
——Table C.1 of 2007 edition is deleted.
This part was proposed by China Petroleum and Chemical Industry Association.
This part is under the jurisdiction of National Technical Committee on Rubber & Products of Standardization Administration of China (SAC/TC 35).
The previous editions of this part are as follows:
——GB/T 3780.2-1983, GB/T 3780.2-1994, GB/T 3780.2-2003 and GB/T 3780.2-2007.
Carbon black—
Part 2: Determination of oil absorption number
Warning: It has been assumed in the drafting of this part that the execution of its provisions is entrusted to appropriately qualified people with practical experience in formal laboratories. This part does not address all potential safety problems. It is the responsibility of the user to adopt appropriate safety and health measures and to ensure compliance with any national regulatory conditions.
1 Scope
This part of GB/T 3780 specifies the method of measuring the oil absorption number of carbon black by instrument method and manual method, and the instrument method is the arbitration method.
This part is applicable to carbon black for use in rubber industry and colour carbon black.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
GB/T 3778 Carbon black for use in rubber industry
GB/T 3780.8 Carbon black—Part 8: Determination of heating loss
GB/T 7044 Colour carbon black
GB/T 8170 Rules of rounding off for numerical values & expression and judgment of limiting values
GB/T 15338 Carbon black—Validation of test method precision and bias
3 Principle
3.1 Instrument method
3.1.1 The aggregation degree of carbon black particles influences the technological process of carbon black rubber compound and the use property of vulcanized rubber. The void volume of the carbon black aggregate depends on the aggregation degree of the carbon black particles, and can be obtained from the volume of oil absorbed by the carbon black. Thus, the oil absorption number of carbon black may be used as the measurement of the aggregation degree of the carbon black particles.
3.1.2 Oil is added by means of a constant-rate buret to a sample of carbon black in the mixing chamber of an absorptometer. As the sample absorbs the oil, the mixture changes from a free-flowing state to one of a semi-plastic agglomeration, with an accompanying increase in viscosity. This increased viscosity is transmitted to the torque-sensing system of the absorptometer. When the viscosity of the mixture reaches a predetermined torque level, the absorptometer and constant-rate buret will shut off simultaneously. The volume of oil added is directly read from the constant-rate buret. The volume of oil per unit mass of carbon black is the oil absorption number of carbon black.
3.2 Manual method
Add oil to a certain amount of carbon black samples at a certain speed, and blend, stir and roll the mixture on a glass plate with a glass rod, so that the mixture changes from a free-flowing state to a semi-plastic agglomerate until the carbon black is all in the specified shape and can be rolled onto the glass rod completely, without oil mark on the glass plate.
4 Test conditions
Laboratory ambient temperature: (23±5)°C. The experimental equipment and reagents used shall be kept at laboratory temperature for 24h.
5 Reagents and materials
5.1 Dibutyl phthalate (DBP), of which its property should meet the standard value for measuring standard reference black, shall meet the following requirements:
a) DBP oil, paraffin oil or epoxidized sunflower oil may be used for N series granulated carbon black listed in GB/T 3778 classification system.
b) For the test of oil absorption number (OAN) of some special carbon black (including powdered carbon black), the test results of paraffin oil or epoxidized sunflower oil may be different from those of DBP oil.
c) DBP oil shall be used for arbitration test.
5.2 Paraffin oil, of which its property should meet the standard value for measuring standard reference black.
5.3 Epoxidized sunflower oil, which should be stored at 7°C~30°C.
5.4 Standard reference black.
6 Instruments and equipment
6.1 Analytical balance: with a division of 1 mg.
6.2 Oven: in gravity convection type, capable of maintaining (125±2)°C.
6.3 Scraper: it should be made of rubber or other non-metallic materials with a length of about 100 mm.
6.4 Carbon black absorptometer: equipped with a constant-rate buret that delivers (4±0.024) cm3/min.
6.5 Microburet: with the minimum division of 0.02 cm3.
6.6 Glass plate: with a dimension of 170 mm×140 mm×4 mm.
6.7 Glass rod, ɸ7 mm~8 mm in diameter, about 300 mm in length.
6.8 Desiccator.
7 Samples
Samples shall be taken in accordance with the requirements of GB/T 3778 or GB/T 7044.
8 Test procedure
8.1 Instrument method
8.1.1 The test samples and the test standard reference blacks shall be the reagents of the same batch.
8.1.2 In accordance with GB/T 3780.8, use an appropriate container to dry enough carbon black samples in an oven at (125±2)°C, and then take out and place into a desiccator to cool to room temperature for standby.
8.1.3 Calibration and inspection of constant-rate buret shall be carried out according to Annex A, and the calibration and standardization of absorptometer shall be carried out according to Annex B.
8.1.4 Weigh the carbon black sample (accurate to 0.01g) according to the carbon black type and its sample mass listed in Table 1.
Foreword i
1 Scope
2 Normative references
3 Principle
4 Test conditions
5 Reagents and materials
6 Instruments and equipment
7 Samples
8 Test procedure
9 Test data processing
10 Precision
11 Test report
Annex A (Normative) Calibration and inspection of constant-rate buret
Annex B (Normative) Absorptometer and its calibration and standardization
Annex C (Normative) Determination of maximum torque
Annex D (Normative) Pre-polishing procedure of newly replaced stainless steel mixing chamber
Annex E (Normative) Evaluation on mixing chamber of absorptometer
