Generally, you probably wear sunscreen when you’re out in the sun to protect your skin from “UV damage." And if you don't: you should. The skin damage done by UV, or ultra violet light happens on a molecular level, specifically occurring to DNA molecules. To quote my mom: "The Sun is stronger than it used to be." Which isn't exactly true, but you get the point.
UV damage is also a problem for plastic polymers. Polymers are composed of long chains of molecules, mainly hydrocarbons, the chemical structure of which determines specific mechanical properties.
Exposure to UV, especially for extended periods of time, can cause serious damage to polymer molecules therefore causing photodegradation which negatively affects the appearance and, most importantly, the mechanical properties of the polymer. Yeah, okay, okay: so what are we getting at here?
Your prints! When you're outside, the there are still problems with structural breakdown as the UV light hits what you've made. Which is no good, not fun, no thanks. What can you do? Well blocking UV with paint is a good option, but that’s just more work and can wear off of mechanical parts.
Follow the sunscreen metaphor: your skin's natural reaction UV radiation is to produce melanin, which among other things, can help absorb and scatter UV to prevent damage. Thank you, evolution. The same principle of adding a substance that absorbs and protects against UV is applied in the plastics industry and that's exactly what we're working on here at Filabot. We're trying to work on a cheap and extrudable UV additive to make more durable prints and parts.
PETG has great mechanical properties and is very comparable to PLA as far as “printability” goes so it is one of our favorite materials to use. However, PETG is no exception to the UV damage problem. Currently we are testing PETG UV stabilizers and absorbers to make this polymer more durable for outdoor use. If you've been reading this blog, you might remember Kevin's tail light print that currently does not have a UV additive. This is an example of an application we will use to test the performance of the UV additives, making sure that prints for outdoor use will stand up to the power of the sun.
Check back on an update where we'll share some test results, problems and solutions. Eventually we will be offering an additive on our site in the future!
Thanks for reading! And happy filament Friday!
The Filabot Team