Medical Materials
with a PPS plastic alloyed with glass, mineral and graphite. “Well-wearing machinable brass generally has lead in it in order for it to achieve those properties,” Kvalo explained. The PPS alloy, like brass, is “very resistant to hot water, very resistant to massive fluctuations in temperature that you see in a plumbing situation, and it wears real well—parts made from it can last 20–30 years”—but doesn’t contain lead. EVCO is working with a customer to bring the material into the medical arena (and no, for the sake of customer confidentiality, he can’t name the company).
From Plastic to Plastic If the industry’s move from metal to plastics bring pain to metal suppliers, they can take comfort from knowing that they’re not alone: a range of plastics too are being replaced by new and better formulations, and often for the same reason: the new stuff is either more cost-effective or safer than what it
and incineration is a preferred way for hospitals to dispose of medical waste—PVC emits chlorine gas.” Chlorine gas—the scourge of the battlefields of Europe in WWI. “PVC is probably one of the cheapest thermoplastics avail- able today—still is. But because of these concerns, we’ve been trying to steer customers [in all industries] away from it. If a customer comes to us requesting to have something made from PVC, we’ll want to talk to them about it,” Kvalo said. “There might be some better materials that cost a little bit more but that won’t lead to the problems that can come with PVC use.”
The ‘End-of-Life’ Discussion
Mike Kvalo understands what some in the industry are still coming to grips with, namely that in medical, as in other industries, sustainability concerns are not going away. “In our initial quality planning meetings with a customer, long before we cut any steel for a new mold, we talk about ‘end-of-life’ considerations for the product,” Kvalo said. “We ask, ‘How are you going to recycle this? How are you going to dispose of it?’ Questions like that, just to get the conversation going. Of course, our customers are concerned about the environment, and they’re concerned about safety, too. So we have these questions on our checklist and make sure these issues are raised up front.”
Ecomass Compounds are a line of patented, nontoxic, high-density thermoplastic composite materials that can be processed on conventional injection molding, compression molding, and extrusion equipment.
replaces. The poster child for a plastic that is being shown the exit in many medical applications is PVC.
“When I started in medical device R&D 30 years ago, PVC was pretty much ubiquitous in the industry, used in tubing, in shunts, drains, and all kinds of devices,” Kvalo remembered. But, as has been widely reported in recent years, PVC has toxicity concerns—not only for patients but also to the environment at large. “When it is incinerated—
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Finding the right substitute for PVC depends on how the product is used. “This is where we’ve really got to apply intelligence,” Kvalo said. “What does this thing have to do? What kind of temperature range will it see? What kind of chemicals will it be exposed to? Does it need to be
clear or is it light-opaque? What’s the expected life? Is it a single-use disposable device?
“When someone comes to me and says they want to make a single-use medical device, probably the first question I’m going to ask is, 'Is it going to be sterilized?' If the answer is ‘yes,’ then my next question would be, ‘Can you use polyethylene?’ Polyethylene is cheap, readily available, nontoxic, and easily re- cyclable—it’s the same stuff that milk jugs are made out of now.
Photo courtesy Ecomass Technologies
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