Why Do We Perform Aging Studies?

The world is a punishing place for polymers. Just like humans can experience sunburn and frostbite, polymers that are out in the elements are at risk as well. While polymers don’t wrinkle or experience other issues from that sort of exposure like we do, they can still bend, break, or fail from exposure to harsh elements.

While we’ve talked about aging plastics before, we want to talk about what aging studies simulate and what function they serve. The wide range of testing environments, study lengths, and product abilities makes this a particularly interesting form of chemical analysis that is often paired with physical testing.

What is an Aging Study?

When we talk about an aging study, we’re usually talking about stability testing. The key in a stability study is to monitor how results from various tests change over time in response to aging. These studies might include, among others: degradation products analysis, remaining additives content, or molar mass distribution. Each of these tests have varying results throughout the life of a given product.

From medically implantable or resorbable products, to plastic pipes and rubber products, no two studies are ever quite the same in terms of our testing capabilities. During stability testing, we seek to simulate the conditions a product might face during its lifespan. For instance, PVC pipe is likely to see damage from temperature fluctuations, UV exposure, and oxidative reactions. Over the life of a product, this can weaken the material and eventually cause failures.

Sometimes, before we can test anything, we need to figure out the simulation itself. How could we simulate a human body in order to test implantable products? If we can’t test in a real body, we created an accurate simulation instead. For example, we can perform a stability study where the product is aged in a phosphate buffered saline at 37°C to simulate conditions in a body, in real time. The same study can then be accelerated by raising that solution to 50 degrees Celsius. In addition to in-vitro (simulated body conditions) aging studies, we occasionally test samples for in-vivo (in a living host) aging studies as well. For this type of study, our clients will send us explanted materials which have been inside a host for a certain amount of time.

With an aging study that might continue for anywhere between 6 weeks and 5 years, these sorts of analysis are hugely important for product testing.

What industries benefit from stability testing?

Polymers are some of the most common materials you come into contact with everyday, from your toothbrush to the pipes delivering water to your sink. On your way to work, the tires on your car and polymer-based fuel lines are all subjected to a daily assault by the elements. All those products need to be stable for long periods of time: pipes that crack after one winter and cars that break down after a hundred miles aren’t very useful.  

Automotive components, rubber materials, and medical devices are just a few of the many materials that can benefit from stability testing. As these materials get older, many mechanisms can cause aging–and potentially degradation. The aging rate of these products is determined by the specific environment to which a material is subjected. This is why it’s important from a testing perspective to be able to test materials throughout their lifespan. Some products, like internal medical devices, are tested for a duration that corresponds to the length of time they’re intended to be inside the body. Other materials, like plastic pipes in your home, are expected to perform without failure for many years. These sorts of tests can be conducted for years or accelerated to simulate a longer span of conditions.

These stability studies give our clients vital information about how their products will perform over time. They help our clients feel confident in their decisions to use a particular product, such as a pacemaker. And the variety of testing environments as well as the challenge of recreating them makes our jobs exciting!

Interested in stability and aging studies and want to learn more?? Contact us today to talk more about our capabilities here at Polymer Solutions.

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