Tech Talk Blog

Now that we’ve established the importance of bag selection in accelerated aging, let’s move on to temperatures.

The aging process subjects samples to elevated temperatures for specific periods of time to simulate the effects of real-time aging.  It is usually required in the testing of medical equipment such as diagnostic devices and surgical implements, and also in aerospace applications.

We’ve noticed the tendency for keeping testing temperatures too high.  By maintaining too high of a temperature, unintended physical changes such as melting may occur.  One must consider the most likely temperature extremes a device would see in practical use and test the device at that temperature.  Another temperature guideline is the Arrhenius reaction rate function, or “10-degree rule.”  This function states that a 10° C increase or decrease in the temperature of a homogenous process results in approximately a two times or ½ time change in the rate of a chemical reaction.

Share with us your experience with temperature testing.

Accelerated aging is a testing method that enables us to estimate the potential lifespan or shelf life of a product when actual data is unavailable.  For instance, products may be subjected to unusually high levels of stress, or mechanical parts may be run at speeds far above normal.  In the case of polymers, they may be kept at elevated temperatures to study the subsequent chemical breakdown.

But what type of product bag should be used in an accelerated aging test?

There are three common options:

1)      Polyethylene — is inexpensive and readily available, but offers a low melting point.

2)      Polyester — offers a higher melting point and can withstand a rigorous aging study, but is more expensive and not widely available.

3)      Aluminum— can be a good option, but is not widely used.  Aluminum is inexpensive and able to reach a higher temperature.  However, aluminum bags are difficult to seal completely (much like foil).

Bag options must be closely considered to ensure a successful aging test. In accelerated aging for medical applications, for instance, we need to determine whether to keep all of the parts in one bag or in separate bags.  It’s best to duplicate the method most commonly used in the real-life environment.

Tell us about your experience with accelerated aging. Check out the Video Learning Center for more information, too!