When we speak of memory in plastic materials, we are talking about a plastic parts ability to return to its original shape after it is deformed in some way. More specifically, we are talking about a part being able to return to its original shape after being held in a flexed position for an extended period of time.
The question is, what makes a material have good memory and what materials are best used for applications that require this property?
Nylon is one of the oldest and most commonly used thermoplastics but there still seems to be a lot of confusion about properly drying nylon and in general about how nylon is affected by moisture. Moisture in the raw material causes many processing issues and part failures and the affects that moisture has on molded parts seems to confound people as well. I hope in this article to clear some of this up.
One the biggest technological advancements in plastics over the last 30 or so years have been the improvement in UV stability. I can remember how fast vinyl dashboards in cars used to split and crack from sunlight exposure. Today, you rarely see that until the car has been in the junk yard for a few years. Even white vinyl siding and fencing seem to hold their color reasonably well for a decade or more. This is thanks to additives manufacturers developing really sophisticated stabilizers and anti-oxidants that can be compounded into various plastic materials.
In this post, I wanted to de-mystify what causes UV damage to plastics and how UV stability is tested.
There is an excellent albeit highly technical article in the April 2016 SPE magazine, Plastics Engineering, about the differences between thermoplastic elastomers (TPE) and thermoset rubber. You can read it here.
Because I talk primarily about thermoplastics here at The Weekly Pellet, I thought that I might expand on the article a little bit and talk about the different types of TPE that are commercially available.