Scientists at Orion S.A. have published “Carbon Black” in the Encyclopedia of Polymer Science and Technology Online. The article is the most comprehensive and updated source of information about the material that is essential to a wide variety of products we use in our everyday lives.
For those who have a deep technical interest in carbon black, here is a summary of some of the latest findings included in the paper:
Reinforcement of rubber: Besides carbon black’s morphology, namely specific surface area (STSA) and structure (COAN), the surface energy or surface activity is recognized as a third important parameter, which plays a dominate role in the reinforcement of a rubber matrix. All tests so far indicate that the high-energy centers on the carbon black surface originate mainly from defects and edges of the basal planes and unorganized carbon atoms.
Coloristic properties: Carbon black dispersed in media — for example in plastics — imparts not only a certain blackness but also colors ranging from a bluish to a brownish black. This color range is referred to as the undertone or masstone of the black and is strongly correlated to light scattering. Calculations of the scattering intensity by using Mie scattering theory of particles of 50nm and 200nm can explain why the coloristic impression changes from blue to red for full-shade application and a tinting application.
Electrical conductivity: First, it must be mentioned that all carbon blacks are conductive due to their graphitic nature. The electrical conductivity imparted by carbon black is used in various applications — for example, for lithium-ion batteries, high-volage cables and fuel hoses. This article explains what is meant by an ultra-conductive carbon black and explains the impact of carbon black concentration, specific surface area, structure and dispersion on the conductivity in an application. The electrical conductivity of a carbon black filled compound depends strongly on the gap size between adjacent aggregates, meaning that direct contact between the aggregates is not necessary for establishing a conductive network.
Structure breakdown: It could be shown that an aggregate breakdown can be analyzed by applying aggregate-size distribution (ASD) measurements before and after exposing the carbon black to high pressures. A structure breakdown cannot be observed for standard ASTM grades such as N220 or N134. The breakdown of aggregates tends to occur in large aggregates. Hence, the probability of aggregate breakdown is higher for carbon black with a high OAN (> 150).
Sustainability: It was demonstrated by Orion that virgin furnace blacks can be produced using renewable plant-based-oil, tire pyrolysis oils and bio-circular feedstocks.
