Graphene versus carbon black for polymers

Did you know that carbon is what gives rubber tires their black color, but also  improves its material properties? Material development is ongoing for virtually everything right now, including rubber, which is used in tires, tubes and gaskets. Much of this development is based on carbon additives. 

Carbon black is the most used form of carbon-based additive to reinforce rubber in the industry today as its electrical and thermal conductivity makes it an additive of choice where static charge dissipation and temperature management is required, such as in tires.  

So, carbon black seems to work quite well, but what if you exchange it with graphene?  

Carbon is a fascinating element, since it can form different allotropes with different properties – for instance, diamond is a much stronger material than charcoal, even though both consist entirely of carbon. In a similar manner, graphene is a better suited material than carbon black if you look at their intrinsic properties. Graphene also provides the black color when added in bulk, and is both much stronger and more conductive than carbon black. Andrea Spanou, Research and Development Engineer at Graphmatech in Uppsala, Sweden, set out to explore the difference. 

Comparing carbon black with graphene 

Carbon black is the standard industrial choice right now, but thanks to the properties of graphene, there is a high interest in replacing carbon black with this exciting material.  To assess this potential, Graphmatech’s team performed a comparative study. The study focused on the electrical conductivity within rubbers. Several samples of carbon black high-quality grades and graphene rubber composites were prepared to assess the effect of their concentration within rubbers. The samples were tested according to IEC standards (IEC 2016 standards, section 5.3.3.2).   

Andrea, what did you find out? 

We saw that graphene reached percolation at lower concentrations than carbon black. That means that a lot less graphene is required to achieve the dissipative properties of carbon black. At the concentration where carbon black was showing dissipative properties, graphene was already entering the conductive region for rubbers. This unlocks more possibilities beyond static charge dissipation, such as sensing and communication with the system the rubber is used in.   

Were you surprised by these results? 

I was expecting that graphene would perform better than carbon black in terms of conductivity. What I did not expect was the magnitude at which we saw improvement. It was almost impossible to compare the samples as we were already in another application range when using the same concentrations. And this is after manufacturing the composite rubbers using technologies specifically produced and tested for carbon black – not graphene.   

Isn’t it much more expensive to use graphene than carbon black? 

The quick answer is yes – today graphene is more expensive than carbon black, especially for dissipative applications. Part of it is because graphene is not yet as widely produced as carbon black and because the industry is more accommodated to carbon black. The amount of graphene required is however substantially lower than that of carbon black, which means that the price difference is mitigated. However, there is more to the comparison than just the price – graphene owns sustainability advantages over carbon black. Sourcing of carbon black is solely based on incomplete combustion of heavy petroleum products. Graphene however can be obtained by exfoliating naturally occurring graphite or recycled graphite. Therefore, graphene as a product has a substantially lower carbon footprint compared to carbon black.    

What industries and applications do you think would benefit the most from exchanging from carbon black to graphene? 

We can unlock more conducting regions which opens up several opportunities. Think of how often you use rubber every day, from the car you drive to the soles of your shoes. Now, replace that common rubber with a semi-conductive graphene containing rubber. You have just incorporated a resistive sensor in your system without changing or adding more steps to the manufacturing process. Is graphene the facilitator for the internet-of-things and global connectivity that we’ve been talking about for 20 years or so? Well, this is for the industry to find out.   

You now explored resistivity and conductivity. Are there any other comparative tests that would be worth doing?  

The combination of graphene properties is truly attractive in the transition to a more sustainable world: thermal, conductive, mechanical, tribological, just to mention a few.  By investigating all properties that carbon black is used for today, we can truly identify graphene’s position in this industry

If I want to explore the advantages of graphene composites for polymers, how can Graphmatech help out? 

Graphmatech produces and sells masterbatches with all polyolefins (PEs, PP) and are working on formulations for engineering polymers such as PA and POM. If you want to improve the characteristics of your polymers with graphene composites, please contact [email protected] for a discussion on how we can develop together.  

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