Learning rubber

TCU physicist Waldek Zerda is helping tire manufacturers reinvent the wheel

By Nancy Bartosek

It's been called the largest vehicular product crisis in this country's history and one of the most puzzling safety issues in decades. Since the early 1990s more than 100 deaths and many serious injuries were linked to Ford Explorers when certain Firestone tires blew their treads. In December, an internal Firestone investigation revealed that while Ford vehicle design and customer tire abuse were factors in the deaths and injuries, faulty tires did play a part in these tragic accidents. More than 6.5 million tires manufactured by Bridgestone/Firestone Inc. have been recalled.

In a small office in the bowels of the Sid W. Richardson building, physicist Waldek Zerda shakes his head and pauses when asked if he knows what went wrong with the Firestone tires.

"I think we know what the problem is, butÉ," the soft-spoken researcher said, a smile crossing his normally serious visage. "No, I don't want to make a statement. What they will do, I don't know. But I think our work will help them understand polymers in tires and polymer reinforcing mechanism." A quintessential researcher -- quiet, introspective and deeply fascinated by minutia -- Zerda takes a very close look at what makes a tire a tire.

The lean Polish native stepped from behind his desk, in one hand a pale-yellow glob -- rubber -- and in the other a small vial of black powder -- Zerda's expertise.

"I will show you this but not invite you to touch it," he advised as he shook the vial. Called "carbon black," it is produced from oil and is the same substance that clings to the walls of your fireplace. Simply put, soot.

In the limelight. Patience is not only a virtue to a physicist, itŐs a necessity; setting up the path of the green laser used in ZerdaŐs unique microimaging process takes two full days. Another of his current projects is developing diamond-hard tips for RockBit International oil-well drills, such as the one he is holding in the photo on the opposite page.

About 50 percent of the tire your car rolls on is made from it. The tire manufacturers get different grades of carbon black and mix it with polymers (various rubbery substances) to create a product with specific properties.

Different parts of the tire need composites of various properties -- the tread must be stiff and hard, the sidewalls soft and pliable.Tire makers like Firestone bond these polymers together. Chemistry is not at work here, but rather pure physics. Pressure, heat and time. Problems arise when the various parts -- usually the tread to the body of the tire -- don't adhere properly.

Zerda and his graduate students, along with scientists from the Sid Richardson Carbon Co. and ExxonMobil (which both fund Zerda's research), have found a way to look at the molecular structure of these composites.

This unique mapping process identifies the distribution of the composites down at the molecular level to understand the way they behave under different circumstances. The information will allow tire engineers to see precisely how the various polymers are distributed in the tire, thus helping them to develop better ways to build a tire.

"The goal is to help them manipulate and control the process," Zerda said. "With this information, they can change manufacturing processes and make a new grade, better. That's a very important issue."

Though Zerda's method of looking at everyday products at the molecular level may affect where the rubber hits the nation's roads, it travels well beyond the steel-belted radial. His understanding of polymers naturally fits with work he is doing with other forms of carbon black. Diamonds, graphite, coal and coke used in steel manufacturing are all based on the element carbon.

Marvin Gearhart, CEO of RockBit International, wants a stronger oil drill bit so Zerda is using inexpensive, man-made diamond crystals to create a diamond-hard tip for the bits. Texas Instruments is looking for a better way to protect their silicon chips.

Zerda works to devise a way to place a microscopically thin diamond film over the top of the chips. And Chevron Corp. needs to eliminate carbon buildup in engines. Zerda is investigating the microstructure of the deposits so they can find additives that will better breakdown the buildup.

"I never wanted to do research for the sake of research," Zerda said. "I wanted to find possible connections with commercial applications. "Knowing I'm doing something that will help improve the world is a nice thing."

This contour map depicts the distribution of two polymers, Exxpro and BR, the latter a typical polymer in tires. Blue indicates high concentration of Exxpro, red areas enriched in BR. This sample -- less than the width of a human hair -- demonstrates poor mixing. Ideally, the two polymers should be mixed evenly with no increased concentration of any of the ingredients at any given spot. How does Zerda create the image? A laser directed at the sample reflects many different colors, with different polymers producing different colors.