The mileage effect

If you are an ambitious cyclist, you may have already dreamed of defeating Mont Ventoux in the South of France. Its climb is more than 20 km long and has an average gradient of 7.5%. The good news is: With our Silica/Silane Systems you need less effort to reach the peak. Used in tires, our rubber ingredients significantly reduce the rolling resistance, which minimizes the muscle power needed on your rides.

The muscle power of a car comes from fuel or the wall socket. Since mobility costs are rising and environmental laws are getting stricter, car producers put a focus on energy effectiveness: They are desperately trying to make cars more aerodynamic and lighter, but simply changing the tires could already make a huge difference …

Our Silica/Silane Systems can reduce the rolling resistance of a tire by up to 35% compared to a tire that only uses carbon blacks. What does that mean?

Reinforcement fillers are key ingredients in the rubber mixture of tires. Without those fillers the tire would be far too weak for a rough life on the street: It would wear out after just a few miles. There are mainly two types of fillers that give tires mechanical stability: the traditional one is carbon blacks; the more elaborate ones are our Silica/Silane Systems. In this article we will compare the performance of tires using one or the other.

When a tire rolls over a road, it has to deal with a lot of mechanical stress: friction, pressure, compression. So, there’s a lot of movement going on between the flexible polymer chains within the rubber. And with every movement some moving energy is transferred into heat. You may still have a vague memory of your physics classes, where the law of conservation of energy was discussed. If so, you will easily understand that the moving energy used to produce heat cannot be used for moving anymore. So, the rolling distance of the tire is reduced.

That is where our Silica/Silane Systems come into play. Every silica/silane particle is like a tiny octopus with lots of sucker cups on every arm. Every sucker cup is a contact point that bonds the polymer chains within the rubber. All those bonds allow less internal movement. Less internal movement equals less heat generation. And less heat generation equals less energy loss. Which leads to a considerably longer rolling distance as well as reduced energy needs and reduced costs.

But there’s more good news: Car, truck, bus, or bike tires using our Silica/Silane Systems do not only have a lower rolling resistance. They are also characterized by improved safety factors such as wet grip and a shorter braking distance on wet roads, without compromising on the abrasion resistance. Find out which other effects our products have on the performance of rubbers in our next effects profile. 

Back in 1992, the implementation of our first Silica/Silane System as a highly efficient reinforcing filler system for treads was a game changer in the tire market. For the first time it was possible to push boundaries in all three categories of the magic triangle of tire performance: rolling resistance, abrasion resistance, as well as wet traction and braking. The marketing was concentrated on fuel savings, so the so-called “Green Tire” was born.

The chemical bond between the filler and the rubber mixture is key in a tire’s ability to absorb and transfer the various forces that act upon it. Unfortunately, the polar silica is not fully compatible with non-polar polymers – it needs a coupling agent to bond the two. This coupling agent is bifunctional organosilane that reacts first with the silica surface during mixing and later to the polymer during the vulcanization process, forming a strong chemical bond between two otherwise non-reacting materials. The basis for that is our product range of precipitated silica especially for the tire market, known under the brand of ULTRASIL® and e.g. Si 69™.

Evonik is the only company worldwide that produces both synthetic amorphous silica and organosilanes for rubber applications, providing them as well-coordinated Silica/Silane Systems. With great advantages for a variety of applications:

• Passenger cars: The use of our Silica/Silane Systems in tire treads reduces the rolling resistance by up to 35% which can reduce the fuel consumption by 8% and extend the range of electric vehicles by 8%.
• Trucks and buses: Energy-saving tires for trucks and busses are relatively new to the market because, in the past, their abrasion resistance was too weak for heavy-duty use. But Evonik has done pioneering work and developed a silica/silane formulation and processing technology which enhances wet grip and reduces rolling resistance by up to 20% without deteriorating the abrasion resistance and the lifespan of a truck tire. So, trucks and buses can save both energy and money.
• Bikes: You can experience how energy demanding mobility is, when you ride a bike. The good news is: Cyclists can also take advantage of reduced rolling resistance, because our Silica/Silane Systems are used by manufacturers of bike tires too – especially for racing bikes.
• Conveyor belts: When it comes to mechanical forces, conveyor belts are very similar to tires. As an ingredient of the rubber dough, our silica/silane agents do the same job as in tires: They ensure that less moving energy is converted into unwanted heat. So, less power is needed to drive the conveyor belt which results in reduced energy consumption and reduced operating costs.

Unfortunately, it’s not easy to find the best filler for your application area. But since we are the inventors of the original Silica/Silane System, we have more than enough experience to help you find the ideal “recipe” for your rubber product. Usually, our Silica/Silane Systems can be added during the regular production process so that no extra equipment is necessary. Just make sure the ingredients are added at the recommended temperatures to get reliable results.

The storage stability of our silica products is also very reliable: When you keep silica in its original packaging in a dry environment, so that it cannot absorb moisture or volatile organic substances, you can store it for two years or even more. 

We developed a formulation which reduces the rolling resistance of truck tires by up to 20 % without deteriorating the lifespan.

It is considered that road traffic accounts for approximately 15% of total CO₂ emissions. But that is only one of many aspects our Silica/Silane Systems help to improve:

• Due to the reduced rolling resistance, our Silica/Silane Systems help to reduce the fuel consumption of combustion engines and the energy consumption of EVs by up to 8%.
• Our Silica/Silane Systems helps to raise the abrasion resistance of tires which reduces the emission of microplastic – a topic that is especially important for heavier EVs or trucks.
• In our portfolio, we also offer low VOC silanes that help to reduce total ethanol emissions during the production of all kinds of rubbers.
• Recently we developed our ULTRASIL® eCO grades which are made of sustainable raw materials, such as rice husk ash or quartz waste.
• On top of that we provide tire manufacturers with comprehensive life cycle assessment (LCA) data.

Another important point is: All silica agents from Evonik are amorphous silicas. Unlike crystalline silicas, amorphous silicas are classified as harmless to humans and the environment. Which means: Evonik silica is safe silica. So, our products are approved for use in food, feed, and pharmaceuticals. The safety of silica as a food additive was repeatedly confirmed by the European Food Safety Authority. Additionally, our silica products received an OMRI Listed® Certification. Which means, that they are proven suitable for organic farming. Please find more facts on the safety of silica in our FAQs section.

Evonik operates nine production sites for precipitated silica and three for silanes around the globe. So, we are able to service our customers locally wherever they are.

If you have questions about the application, processing or storage of silica and silanes, please don’t hesitate to ask. We are quite sure that we can offer you a practical solution: Simply send us a message at ask-se@evonik.com or press the contact button above. Our experts will contact you as soon as possible.