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.
Everyone have a fun and safe 4th.
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.
Back when everyone was running injection molding machines with plungers, if you needed to color material, you had to have it pre-colored at a compounder. The compounder would melt the natural material down, blend in raw pigments and other additives and then re-pelletize the material.
The advent of screw type injection machines and color concentrates significantly reduced the cost of coloring plastic materials. However, running material blended with color concentrate has its challenges. It has to be mixed carefully and the material has to be processed carefully to get good results. Sometimes, even if you do everything right, you end up with nothing but problems.
I’m not sure if anyone does this anymore but when I was a kid it was great fun to shuffle your feet on carpeting and then zap your unsuspecting sibling with a nice static shock. This typically worked best if you had nylon carpeting and it was nice and dry in the house like in the winter time.
This worked because plastic is a great insulator and thus cannot dissipate static electricity very well. When we need to reduce the likelihood of static build up in plastics, we have some options. There are materials described as having anti-stat additives and other materials described as being statically dissipative and still others as being conductive. What’s the difference?