PFAS, traceability challenges affecting consistency for custom mixers

AKRON—Conformity in batch production in the custom mixing business is fundamental, and it is a holy grail of sorts for health care elastomers.

The implications of batch inconsistencies are acute, as they can cause major delays in the development of new materials.

A panel of experts at the Healthcare Elastomers Conference May 8 offered some advice for repeatability in the mixing process and current challenges posed by environmental regulations, including the measures potentially looking to ban PFAS chemicals.

"From a lab testing side, batch-to-batch variation can break down into two issues: is it a material issue or a manufacturing issue? We want to make sure the raw materials are consistent," said Kylie Knipp, senior technical account manager for Ravenna, Ohio-based Ace Laboratories, a rubber material testing firm. "If it is on the manufacturing or process side, then processability testing is needed.

"This is where we would start with inconsistencies."

Automation, artificial intelligence and data integrity are other remedies to avoiding batch variations, according to Khaled Boqaileh, CEO and co-founder of Kitchener, Ontario-based LabsCubed, which offers automated tensile testing equipment.

"We do not seek conformity in batch similarities, but certainly our customers do," Boqaileh said. "And this is where automation can come in to assist them ... in batch-to-batch uniformity."

Boqaileh said the complex nature of the testing processes and associated analytical data collection lend themselves well to simulation.

"Adding in a simulation piece and accelerating that piece, we know that will be the main thing," Boqaileh said. "And I would say the data integrity piece is the most important piece—not the AI piece."

The choice of methods and equipment to use in medical rubber product testing is equally important, according to Ed Terrill, applied research fellow at Akron Rubber Development Laboratory Inc.

He has worked for Goodyear in the polyester, tire physics and compound science departments, as well as for DuPont in textile fiber research.

"The test needs to be specific, perhaps not just tensile," Terrill said. "You can measure dispersion with tensile testing. With a service life of a product, military specifications are a rough guideline ... typically we do not follow them.

"We look at the aging rate, using temperature data to predict service life. Once the physical testing is done, we move to the statistical analysis to find out where is the variation in each step of the process."

Obtaining the right material for analytical testing and benchmarking that material—knowing exactly what goes into a custom mix—is critical.

It is equally complicated, especially since the health care elastomer manufacturing industry exists on a global scale.

"Traceability is always concerning ... you have to be able to track your material," Knipp said. "And this may change your suppliers, where a material might trace to somewhere different.

"But there are ways to fingerprint material to make sure the right material is going in. You can benchmark what you are currently getting, so you have consistent chemical and physical properties—ensuring long-term service life."

This is especially true with fluoroelastomers, said Bill Stahl, who has four decades of product development experience, including 30 years at DuPont Performance Elastomers.

"From a custom mixing standpoint, you want good consistency," he said. "The time of day and the humidity can cause results to vary. We want to make sure the recipe is secure.

"With fluoroelastomers, you need traceability. If the material gets to someone else (without it) they have no idea what is in the rubber compound. If the part fails, there is no way to trace it back. But when you have it, a customer knows exactly what is in the formulation."

Boqaileh noted that traceability can be assisted by entering data in a system—something that automation does very well.

"During the pandemic it became complicated, sort of a firefighting situation," he said. "It will always be an issue of putting data into a system. And, sometimes, that can fall by the wayside."

There is a safety aspect as well, Knipp said.

"With the push to on-shore products (like glove production), people were looking at it from a national security standpoint," she said. "But as on-shoring happens, it can affect raw material availability. What is available in the U.S. can be very different than what is available in Asia.

"There are a lot of things to consider. And we are seeing a push to make sure the data is accurate and repeatable."

Per- and polyfluoroalkyl substances, commonly known as PFAS, are on the minds of many in the rubber product and other industries.

There are more than 9,000 chemicals on the list being considered by the U.S. states and the European Union for regulation.

"People are exposed to the material everyday with coated cookware, fabrics, stain resistance materials, mascara, dental floss, lipstick, pharmaceuticals, and some commercial medicines, including Lipitor and Flonase," Stahl said. "In the health care industry alone, kidney machines use PFAS materials, and they are used in implant devices."

The ubiquity of PFAS materials represents an enormous problem.

"They are used everywhere," Stahl said. "They need to determine what is a good PFAS and what are bad PFAS materials."

These widely used, long-lasting chemicals have components that break down very slowly over time, according to the U.S. EPA.

PFAS traces have been found in the blood of people and animals all over the world and are present at low levels in a variety of food products and in the environment. PFAS are found in water, air, fish and soil at locations across the nation and the globe.

Scientific studies have shown that exposure to some PFAS in the environment may be linked to harmful health effects in humans and animals.

Some of the most common PFAS chemicals include perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA), also known as C8.

These chemicals were once used in substances like fabric and leather coatings, household cleaning products, firefighting foams and stain-resistant carpeting.

Some U.S. and Canadian manufacturers have phased out their use over the past two decades.

"Only a handful are actually dangerous, and regulatory bodies seem to be trying to ban things across the board," Knipp said. "This is driving people to use other options, and certain materials are not easy to replace.

"Other polymers do not perform at the same level."

The chemical manufacturing giant 3M plans to pull out of PFAS materials altogether, Stahl said.

"It started with the health industry when it was determined that some were bad for our health," he said. "Lawyers started filing lawsuits, and the environmental regulatory bodies got hold of it and pointed out all the PFAS that are in the environment.

"We have to do something about this. Major companies are starting to get out of PFAS materials. States are the driving force on this in the U.S., not the federal government."

The EU is expected to vote in September on regulated PFAS uses (eying a full and complete ban by 2050), while states in the U.S. have various timelines for addressing some or all of the PFAS chemicals listed.

"From a materials side with the bans, the challenge is finding other materials that can replace these fluorinated polymers," Knipp said. "Existing manufacturers are looking at other high-end materials."

Stahl added that "Chemours, Trelleborg ... everyone is talking about it."

"If the EU follows through first, this will affect manufacturing in this country and worldwide," he said. "It is very hard to remove this material from the environment. It's been around since the 1930s when Teflon was discovered.

"It's got strong chemistry and it is going to be here for a long time."

Rubber News wants to hear from its readers. If you want to express your opinion on a story or issue, email your letter to Editor Bruce Meyer at [email protected].

Please enter a valid email address.

Please enter your email address.

Please verify captcha.

Please select at least one newsletter to subscribe.

View the discussion thread.