Smithers: 4 trends changing, challenging automotive

FAIRLAWN, Ohio—Like the inversely related points on the "magic" tire triangle, sustainability and performance can be difficult to reconcile.

Whereas some materials might be recovered, circular or recyclable, they often are representative of the polymer material that went into the recovery process. As such, recycled products may not meet necessary performance thresholds.

Brad Sellers, an associate consultant in the Materials Science and Engineering Division with Akron-based Smithers, highlighted some of the myriad materials that can help make both sustainability and performance possible May 10, the first day of the Rubber in Automotive Conference organized by Rubber News.

His wide-ranging talk, "Sustainable Rubber Formations for High Performance," focused on greener carbon black production methods, sustainable tire ingredients and new raw material technology, all at the onset of lightweighting (and electric vehicles).

"When we talk about sustainability, we talk about what is pushing it—and that is the environment, investors, employees and consumers," Sellers said. "We need to look at the big picture moving forward ... because it is a delicate balance of performance, sustainability and unintended consequences."

Here are four takeaways from Sellers' talk.

In its study "The Future of Green Tires to 2027," Smithers identifies material trends in elastomers, fillers and other chemicals—led in part by silanes, which are "critical for green tire rolling resistance reduction."

In short, material trends in the sustainability-performance conundrum are critical to understand, Sellers said, whether they are tire-specific trends, or those that surround the composition of automotive elastomers and fillers.

Sustainability options for NR substitutes include the guayule plant and the Russian dandelion, both hearty plants that can be grown where other natural rubber compounds cannot be cultivated.

"An added benefit here is that these are areas that may not be suitable to (growing) food, so they are not competing with food crops," Sellers said.

In addition to alternative sources for NR, Smithers has identified four, more sustainable methods for carbon black production, including recovered CB from tire pyrolysis, circular CB, methane pyrolysis and renewable CB methods.

"Methane pyrolysis, in particular, is interesting as it uses hydrogen to help produce energy," Sellers said. "This type of material can replace current grades of CB."

Finally, rice husk silica may be the most promising option as a filler to help reduce rolling resistance.

"There is plenty of supply of this waste product to completely take over for (synthetic) silica in the tire industry," Sellers said.

Internal factors in developing a greener tire include a company's sustainability goals, energy consumption, raw material sourcing and recyclability, Sellers said.

External pressures can come from biofuel tech trends, powertrain choices, tire tread emissions and cost, among many other complexities.

Raw material technology is certain to play a critical role.

"Tires can take years to develop, so the speed-to-market really is not there with the product," Sellers said. "In the past, ground rubber from end-of-life tires was only used to replace filler.

"Now, new processes are available allowing for larger (ground rubber) replacements in rubber compounds. This has the potential for a zero waste stream for the rubber industry."

In addition, specialty resins based on crude tall oil and crude sulphate turpentine are available.

"And these deliver sustainable value, helping numerous industries replace fossil fuel-based sources with renewable solutions offering unmatched performance."

As the automotive industry switches to EVs and battery hybrid vehicles and away from internal combustion engines, OEMs need more sustainable options for products to test and work with.

"Improving vehicle performance has traditionally been a key focus area (for OEMs)," Sellers said. "This includes improving fuel efficiency, tire treadwear durability with fewer replacements necessary and load capacity, given the lightweighting initiatives."

In turn, the shift to EVs, like their legacy cousins, will require a balance of the performance triangle between wear, grip and rolling resistance.

"We are seeing a trend to OEMs supporting the desire for longer range and reduced weight," he said. "Battery compartments with seals and gaskets are changing and there are alternate materials for coolant lines."

And in the circulatory system of an EV—which no longer has toxic oils and gasolines coursing through it—coolant lines for the battery compartment is a major consideration for material engineers.

"We need to make sure this sustainability option is not causing unintended consequences," Sellers cautioned.

EVs have driven hose material changes toward nylon and EPDM, using quick connects and some clamping.

And the hose line configurations in EVs require longer runs, which means engineers need to consider higher pump-flow rates, Sellers said.

The Tire Industry Project, being undertaken by the 12 major tire manufacturing members of the U.S. Tire Manufacturing Association and other governmental entities, focuses on 6ppd (and its relatively unknown offshoot 6ppd-quinone, which is killing coho salmon in the Pacific Northwest), dandelion and guayule and a number of other greener production and material alternatives moving forward.

"So how does testing need to adapt?" Sellers asked. "Do we need to look at cold rolling resistance? Or how treadwear is affected? With EVs, people are having to replace the tires much more often than they originally thought."

A recent J.D. Power report confirms this, according to a May 30 Rubber News story, which has EV owners calling out OE tire manufacturers for woefully underperforming treadwear.

"There is a lot of market momentum right now," Sellers said. "There are a lot of options being looked at. We need to offer testing that pushes sustainability as far as it can go without having unintended consequences."