Thermal and Microscopic Analysis of Recovered Carbon Black Material

Carbon black is a highly valuable material used in large quantities (>10 million tons) globally, especially in the automotive tyre industry. The high carbon content of this material means that there is an impetus to transition the production and use of carbon black into a circular process via novel recovery processes, primarily pyrolysis of tyres. 

Tyre pyrolysis is a process that involves the controlled heating of waste tyres in the absence of oxygen. This process breaks down the rubber and other components of the tyres into a variety of products, including recovered carbon black (rCB). rCB is a valuable material that can be used as a reinforcement agent in the production of new tyres, plastics, and other products. The carbon black extracted from tyre pyrolysis is often of comparable quality to virgin carbon black, making it an attractive alternative for manufacturers seeking to reduce their environmental impact.

However, the key functional properties of recovered carbon black (rCB) materials can vary dramatically depending on the rCB chemistry, morphology, and structure. Thus, there is a need to develop robust characterisation methods for this novel material to guide their production and quality control during manufacture.

The Bridge, at the University of Lincoln, UK, is equipped with a range of advanced analytical tools for materials characterization, including scanning/transmission electron microscopes (S/TEM), which have the capability to combine imaging with EDX elemental analysis to investigate chemical composition, and simultaneous thermal analysis (STA), which performs thermogravimetric analysis (TGA) which can be coupled with analysis of the evolved gases via a quadrupole mass spectrometer (MS).

Using TEM, it was demonstrated that it was possible to examine the size and shape of the particles and aggregates that make up the rCB material at the nanometre level, which is vital as nanoscale structures account for the reinforcing properties of rCB materials. In addition, using the EDX detector on the TEM, individual chemical components within the rCB material were identified and characterised. Using the STA-MS, the thermal characteristics of the rCB material were investigated, by heating at a controlled rate, and observing the mass loss with temperature, and the MS was able to identify evolved gases.