In the September/October 2025 issue of the European Rubber Journal , Endurica was listed as having the second most important project for sustainability! The complete list is shown above.
This recognition is especially compelling since all the other companies listed are much, much larger than Endurica.
The Endurica technology enables the prediction of fatigue and damage due to oxidative aging in tires. Truck tires and commercial aviation tires are normally designed for retreading and thus benefitting the circular economy through the easiest path – re-use. One of the chief reasons that these tires are not retreaded is due to the casings having too much damage, and one of the principal damage mechanisms is through oxidative aging.
According to the ERJ article, “retreading can give new life to around 18-20 million tires a year” and the vast majority are truck tires used on tractor-trailer rigs. Imagine 20 million less tires a year going into a landfill. Each retread means fewer raw materials consumed, less manufacturing energy used, and lower CO2 emissions. The article goes on the say, “However, the extended-life tires face a “hidden challenge” in the form of rubber oxidation: a gradual breakdown of the molecular structure as oxygen slowly diffuses into rubber. This can lead to a deterioration of physical properties, including a loss of elasticity, increased brittleness, reduced flexibility and fatigue resistance.”
The technology was developed primarily by Dr Mahmoud Assaad, Sr Technology Advisor, and Jesse Suter, Development Manager for Endurica, together with colleagues at Akron Rubber Development Laboratory (ARDL). The main contributor from ARDL was Ed Terrill (now retired). Ed and Mahmoud had worked on this technology together at Goodyear as part of the long-running Cooperative Research and Development Agreement with Sandia National Laboratories (CRADA) between Goodyear and Sandia.
One of the areas of the technology is called Diffusion Limited Oxidation or “DLO”. This is observed when oxygen diffuses through the surface of a rubber component, it starts to react and gets consumed by the material near the surface, so less oxygen diffuses and reacts on the interior of the component. We can see this experimentally by measuring the local stiffness (modulus) of the air-aged material as it varies through the thickness. Shown below is a plot of local modulus for a 2 mm thick NBR rubber sheet aged at various durations at 125℃ .
K.T. Gillen, M. Celina / Polymer Degradation and Stability 71 (2001) 15-30.
The authors of this work are Ken Gillen and Matt Celina of Sandia, and they were working with Goodyear on this technology. You can see that on the edges the modulus has increased by 2 orders of magnitude due to the added cross-links from oxidation. At first consideration, a higher stiffness could be beneficial for a rubber compound, but in addition to the higher stiffness comes embrittlement that leads to cracks that can propagate and cause failure. The bushings below have oxidative aging on the surface.
Another look at DLO can be seen from the simulation capabilities. Below are predictions of oxygen consumption rate for two tires, a truck tire on the left and a passenger tire on the right. The entire cross section of the passenger tire sees significant oxygen consumption with the minimum being at the belt edge. The truck tire shows less oxygen consumption rate at the belt edge due to the thickness of rubber in this region. However, with extended life from retreaded tires, and possible cracks and damage in the casing can allow a sufficient amount of oxygen to diffuse into the critical belt edge region.
More information on this technology can be found in the recent post by Mahmoud Assaad.
Endurica has additional efforts ongoing for sustainability and environmental impact. One area is aiding the search for a replacement for the 6PPD antioxidant (and anti-ozonate). A viable replacement will need to protect compounds from oxidation which causes a decrease in strength and fatigue life. The Endurica workflows are used to evaluate the performance of proposed replacements.
Also impacting sustainability, Endurica is helping to develop material characterization and durability modeling techniques for Thermoplastic Elastomers (TPEs) and a subset, Thermoplastic Vulcanizates (TPVs). These materials can replace some of the applications where carbon-black filled rubber is currently used. Carbon-black filled elastomers are very difficult to effectively re-cycle. Most TPEs can be recycled, and they typically require a much smaller, and more energy efficient manufacturing process. One publication looking at the use of a TPV for automotive applications can be found here, in the paper titled, “Hyperelastic-viscoplastic and crack growth behavior of thermoplastic vulcanizates (TPVs)”.
The new oxygen diffusion and oxidative aging capability together with Endurica’s other aging analysis methods, including Ozone and anerobic aging effects, provides a complete picture of durability for most elastomers. I plan to discuss more on aging in a subsequent blog.
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