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Tuesday, July 27, 2021

Game Changers: Rubber Cycles Up

[Excerpt from Inside Outdoor Spring 2016]

Rubber Cycles Up

Austin Footwear Labs wants you to leave a better footprint

By: Ernest Shiwanov

In the near future, Austin Footwear Labs’ Tredagain game-changing technology is going to be everywhere due, in part, to the large-scale problem this technology addresses. The issue here is the appropriate disposal of post-consumer and industrial rubber waste. More specifically but not limited to, a landscape littered with used automobile and truck tires.

Until now, there has been no costeffective, scalable and non-environmentally egregious method to handle pre- or post-consumer or industrial rubber waste. The reason is, once batches of rubber are created, they are virtually impossible to separate back into the original components. That limits rubber’s reusability or recyclability. This chemical impasse, in some measure, can be attributed to a one Charles Goodyear.

Tired of tire waste, Austin Footwear Labs and Tredagain sandals are reconstructing rubber
Tired of tire waste, Austin Footwear Labs and Tredagain sandals are reconstructing rubber 

Goodyear, an impoverished inventor, tenaciously worked on improving gum rubber even during stints in debtor’s prison. He saw the material’s upside potential despite its two well-known flaws. During the summer, gum rubber products would morph into glue-like blobs and in the winter turn to inflexible stone. Undeterred by setback after setback, he utilized his engineering savvy from manufacturing agricultural implements and his auto-didactic approach to solve problems befitting a chemist. The year was 1839 and as with many notable discoveries, the solution was found accidently, but not according to Goodyear. In any event, adding sulfur and heat to the gum dramatically changed its physical characteristics to what we now take for granted.

The process of adding sulfur and heat, later named vulcanization by one of Goodyear’s competitors, is what makes rubber so difficult to recycle or reduce back to simple compounds. Think of it like baking a cake. When the cake finally comes out of the baking pan, there are always crumbs remaining in the pan. However, like rubber, those crumbs cannot be gathered together and reduced back to flour, sugar, butter, baking powder, eggs, salt and milk. That is not to say individuals have not attempted to do so. During the years, there have been efforts to utilize waste rubber from tires and other waste-stream rubber with limited success. Yet it took another accident, this time by a professor and research engineer at Kansas State University, to unlock the devulcanization code. Liang-tseng (LT) Fan, distinguished professor at KSU, and Shahram R. Shafie, a veteran process/chemical engineer in both government and industry, were looking for a spot remover for organic-based fabric, relates Fitz Lee, president of Tredagain.

APX, 100% devulcanized rubber ready to be added or upcycled into a rubber master batch as virgin rubber (image courtesy of Tredagain).
APX, 100% devulcanized rubber ready to be added or upcycled into a rubber master batch as virgin rubber (image courtesy of Tredagain).

“At one point they kept thinking they had defective rubber stoppers,” says Lee, “until they realized this was pretty special, and they spent the following few years isolating the phenomenon and optimizing the process.”

Their proprietary Fan Process, named in honor of the late Dr. Fan, uses rubber crumb from tires to devulcanize into APX, a 100 percent virgin rubber or virgin rubber substitute. A patent application was applied for in 2006 and later issued.

In 2007, Fan, Shafie, Lee and a few other colleagues went on to form Green Source Holding Company, a business dedicated around “opportunities that use technology to solve resource efficiency issues.” Austin Rubber Company and Austin Footwear Labs are two of the core businesses. Fan and Shafie’s breakthrough technology is what powers Austin Rubber Company’s breadand-butter product APX.

APX, in turn, is used by Austin Footwear Labs’ Tredagain footwear, Green Source Holding’s demonstration platform for APX. Which is why Austin Footwear Labs’ Tredagain is so special: it is the first use of APX in what is to be a revolution in the upcycling of waste rubber to high-performance second, third or potentially innumerable product reincarnations. The other plus side of APX is its affordability. It is cheaper than virgin rubber with no performance downsides, says the company.

Tredagain’s hand-stitched Woman’s Classic Sandal (sand)
Tredagain’s hand-stitched Woman’s Classic Sandal (sand)

“The best part about our story is that consumers can’t tell we are using APX since quality, durability and performance are not compromised,” says Lee. “Our goal with Tredagain was making fashion, sustainability and affordability come together.”

Lee is quick to emphasize that this product is not recycled. It is upcycled. “No longer is a token 1 to 3 percent of factory scraps as filler (i.e. nonfunctional component in the rubber master batch) going to cut it with the educated consumer. Upcycle not recycle is the new industry standard, and 50 percent is the new sustainability goal,” says Lee.

On the quality and durability side of the equation, Lee’s numbers on APX seem to bear things out. For those familiar with Shore hardness nomenclature, an outsole rubber sample and one with 50 percent APX have about the same value (see table).

Comparison between Austin Rubber APX at 25% and 50% concentrations versus typical rubber used for footwear outsole applications (Courtesy of Fitz Lee, Tredagain)

What’s the maximum amount of APX used in a given master batch?

“Depending upon the specific physical and dynamic qualities you are targeting, there are upper limits for each compound,” Lee explains. “Since APX comes from tires, there will be some physical properties it will not provide on its own, so different virgin materials will need to be added to achieve them.”

Rubber-Recycles-Up_friendsTredagain sandals carry 50 percent loads of APX (with load being the weight percentage of total rubber compound), “but Austin Rubber has hit 80 percent loads on other compounds that do not require the same dynamic properties,” continues Lee. “We have in-house polymer compounding capabilities to help our customers to select the correct compound for their application.”

For now, Tredagain is focused on men’s and women’s sandals, but Lee promises new urban rain boots for Fall 2016. Consumers who purchase online will be glad to see Tredagain ships using recycled packaging, stamped not printed shipping labels and recyclable shape-holding inserts. It’s all part of that better footprint.



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