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UTK-Eastman team develops new method to find flaws in rubber

With a push to get more electric vehicles (EVs) on Tennessee roadways, different aspects of automobile manufacturing have to keep up with the changes those types of cars bring.

The University of Tennessee, Knoxville (UTK) said a standard tire can wear 30 percent quicker on an EV than on an internal-combustion vehicle, prompting the rubber industry to look for improved methods to ensure material sustainability and durability.

That’s where UT Knoxville researchers come in.

A new method to ensure consistency and quality in rubber manufacturing, developed by a research team from UTK and Eastman, is likely to show a real-world impact on material sustainability and durability for products such as car tires.

According to a release from the university, UTK’s Fred N. Peebles Professor and IAMM Chair of Excellence Dayakar Penumadu, along with electrical engineering graduate student Jun-Cheng Chin, postdoctoral researcher Stephen Young, and three Eastman scientists, recently published research aimed at resolving one of rubber manufacturing’s most common challenges: identifying flaws in the material.

The release goes on to explain that rubber contains additives such as zinc oxide and sulfur that work to improve strength, elasticity, and other favorable traits. When the ingredients are not distributed evenly throughout a rubber product such as a car tire, the material will contain flaws that cause the product to degrade prematurely.

Identifying and studying such flaws—a field known as fracture mechanics—is critical to understanding how the material will perform. Yet finding such flaws before they cause problems is an issue that has long plagued the rubber industry.

“The current industry approach is to cut out a small sample of rubber, then observe it under an optical microscope,” Penumadu said in the release. “Not only is this tedious and destructive, it’s unreliable. It requires you to guess beforehand where, in an opaque sample, you need to check for inconsistencies.”

Penumadu’s team has overcome this issue by switching from optical analysis to X-ray computed tomography (XCT). X-rays that pass through the sample are scattered and absorbed differently depending on the materials they strike. A computer then reconstructs a digital 3D model of the rubber’s interior.

“This is a very important point,” Penumadu said. “XCT lets us see the inside of the material noninvasively, and we can actually see the distribution of each component.”

The application of this new method increases the rubber industry’s ability to view and predict flaws and will ultimately lead to more consistent quality and longer-lasting rubber products.

In October the team received the 2021 Publication Excellence Award from the Journal of Rubber Chemistry and Technology for their groundbreaking paper, “Sulfur Dispersion Quantitative Analysis in Elastomeric Tire Formulations by Using High Resolution X-Ray Computed Tomography”, which discusses the new XCT method and their research findings.

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