Carbon black refers to black powdery or granular material, which is composed of many tiny particles with the average particle size of between 10 and 2000 nanometers. It is composedot many carbon atoms buthydrophobic in nature. Carbon black can be prepared by pyrolysis of hydrocarbons such as coal tar or petroleum. It is widely used in tires, colored pigments, conductive additives, electroplating black carbon, printing ink, and other rubber fillers.
The application of carbon black has been studied for a long time around the world. In the standardization of carbon black, the Chinese Ministry of Chemical Industry issued the first standard of GB 12827-91 for the identification of carbon black. The standard focussed on the detection and identification of carbon black by its physical and chemical structure. The specific contents of GB 12827-91 standard include:
- Classifying for carbon black according to its particle size, structure, and nature. The classification includes four kinds of carbon black, namely resin carbon black, lamp black, gas carbon black, and thermal carbon black.
- Performance analysis of carbon black, including carbon content analysis and the detection of heatsensitive indices, oxidation degradation indices, and insoluble sediment indices.
- There are eight methods of identification for carbon black in this standard, including differential thermal analysis, thermogravimetric analysis-mass spectroscopy, thermogravimetric analysis-FTIR, particle size and shape detection, X-ray fluorescence, refractive index and optical microscopy.
The GB 12827-91 standard has provided an essential reference for the research and application of carbon black. In 2008, the China National Standardization Management Committee officially released the Technical Specifications for Carbon Black, upgraded the GB 12827-91 to GB/T 12827-2008. The new standard set the physical index requirements for carbon black, with the scope of application extended to the paint, plastic and other industries that require carbon black for color pigmentation.
Generally, the test of carbon black should follow the standards and regulations of GB 12827-91 / GB/T 12827-2008. The laboratory technicians should strictly follow the procedures in the standards to test the carbon black. First, the sample should be accurately weighed and placed in a grinding mill. Second, prepare the standard sample, and mark it by ink. Third, use the grinders to evenly disperse the sample into the designated containers, and then take them into the furnace.
Fourth, determine the particle size and shape of carbon black. This is done by two methods, namely sieve analysis and electron microscopy. Sieve analysis can be used to analyze the particle size distribution, whereas electron microscope can be used to see the shape of the particles. Fifth, the carbon content, thermal-sensitive index, oxidation-degradation index, and insoluble sediment index of the carbon black sample must be determined. Sixth, take the sample from the furnace and use differential thermal analysis, thermogravimetry-mass spectroscopy and thermogravimetry-FTIR to identify the carbon black. Finally, identify the entire sample through visual inspection and optical microscopy.
In a word, the GB 12827 91 standard has been an important reference for the identification of carbon black in China. Following this standard strictly, laboratories can guarantee the accuracy and correctness of the results of their carbon black tests.
