The density of carbon blacks refers to the mass of carbon black per unit volume, which is divided into true density and apparent density (pour density or apparent density).
The difference between carbon black’s true density and pouring density or apparent density
There are two types of density of carbon blacks . One is the true density, which is determined by the elements and structure (or crystal structure) that make up the carbon black. Unless otherwise specified, the density of carbon black refers to the true density; the other is the true density. Pour density or apparent density, which varies with the processing conditions of carbon black, needs to be measured frequently. Apparent density mainly provides the basis for volume calculation of engineering equipment, packaging, storage and transportation containers. Carbon Black N660
The distance between graphite layers of carbon blacks is larger than that of graphite, and its density is smaller than that of graphite. Carbon black density can be measured by different methods. The most representative testing methods are X-ray diffraction and helium replacement. The density of carbon black measured by different testing methods is different. The density of carbon blacks measured by X-ray diffraction method is generally 2.O4~2.11Mg·m; the density of carbon black measured by helium replacement method is generally 1.84~2.O6Mg·m, while the density of graphitized carbon black can reach 2.18 Mg·m.
About the density of granule carbon black
Pour density is the main indicator of granule carbon black. The so-called pour density of carbon black does not specifically refer to a certain type of carbon black. Both wet carbon black and dry carbon black have pour density. The pour density roughly means the density of carbon black in its natural state.
The apparent density of powder carbon black without granulation (also known as fine powder content) is very small, only between 80-190Kg/㎡. Because of its large size and easy flying, it causes difficulties in the packaging, transportation, warehousing, mixing, processing and dispersion of carbon black.
Therefore, except for a small amount of pigment carbon black that requires powdery form, almost all industrially produced commercial carbon blacks must go through Wet or dry granulation or compression processing. The densification effect of granulation processing effectively reduces the apparent volume of carbon black per unit mass. The pouring density of granulated carbon black is about 300-500Kg/㎡.
Carbon blacks apparent density calculation method
Apparent density refers to the dry mass of material particles per unit volume (including material entity and closed pore volume), also called apparent density. Calculate according to the following formula: ρ’=m/V’
ρ′——The apparent density of the material, kg/m3 or g/cm3;
m – the mass of the material, kg or g;
V′——The volume of the material when it contains closed pores (that is, it only contains internal closed pores and does not include open pores), m3 or cm3.
Usually, the volume formula of materials under conditions including closed pores is measured by the drainage displacement method or the water weighing method.
Application points of carbon blacks density in rubber industry
In the rubber industry, conventional mixing methods are often used to mix a certain mass of carbon blacks into rubber with a known density, and the carbon black density is measured by testing the density of the rubber compound. Carbon Black N330
The density of carbon blacks for rubber measured by this method is generally 1.80 to 1.86Mg·m, and 1.86Mg·m is often taken. The pouring density of powdered carbon black is generally 30~48kg·m, the pouring density of powdered carbon black after densification is generally 8O~190kg·m, and the pouring density of wet granulated carbon black is generally 3OO~500kg·m. m. Carbon black with small particle size and high structure has low pour density. Carbon Black N550
