Physical and Chemical Properties of Carbon Black

Posted by RachelHJM on May 14th, 2017

Carbon black is a kind of amorphous carbon, light, loose and very fine black powder, its specific surface area is large, ranging from 10-3000 m2 / g. It is the product of organic (natural gas, heavy oil, fuel oil, etc.) under the condition of insufficient air by incomplete combustion or thermal decomposition.The proportion of 1.8 to 2.1 natural gas named gas black, lamp black is made from oil, which is made from acetylene said acetylene blac, there are also channel black and furnace black. According to the carbon black performance to distinguish, there are reinforcing carbon black, conductive carbon black, wear-resisting carbon black, etc.

Blackness and particle size
Blackness of carbon black directly associated with the particle size, the smaller the particle size distribution, specific surface area is larger and the blackness of the carbon black is higher.This is because even though the primary particles has fused into original aggregation, its surface area can still play a role. The finer primary particles, so that the specific surface area of condensed matter is large, color is more black and presented uv effect is better. Due to the fine particles of carbon black absorbance is higher than the coarse particle of carbon black, so the tinting strength of fine particels of carbon black is stronger. However, when the particle diameter reduced, the blue light is absorbed by priority, this color become brown. Small primary particles gives carbon black larger specific surface area and increase its dispersion, but general could be adjusted by surface wettabilty to improve the dispersion.

The structure of carbon black
Not only carbon black particles is in the form of primary particles, but in the production of fused into aggregation.This kind of aggregation is made up of primary particles by bonds.In the process of coagulation, which is composed of a large number of chain branch primary aggregation called high structure carbon black. And native agglomerations are composed of less chain branches primary particles, it is called low structure carbon black. The structure of carbon black is morphology of carbon black aggregation, the more and closer chain branches, its structure is higher, conversely, the lower structure.

The surface chemically
Due to different carbon black production methods, surface chemical properties also is not the same.Carbon black surface has different oxygen functional groups, such as carboxyl, aliphatic and phenolic groups, carbonyl, etc. Generally speaking, high oxygen containing functional groups of carbon black enjoys high volatile flux, its color adjustability performance is good and the fluidity is as well as higher.

Moisture absorption of carbon black
Carbon black is a kind of large surface area material, thus it has certain moisture absorption. Moisture absorption of carbon black is mainly determined by surface area. We also can take measures to reduce the hygroscopicity of the product, especially in the packaging, storage and transportation process.Because of high moisture content (moisture absorption quantity) may cause problems for processing, so there is a special packing requirements for some varieties of carbon black.