Summer is here and the heat is on which makes this a good time to point out a couple of things about PLA and remind everyone just how hot it can get in your car. It is generally recommended that you store PLA in a cool dry place. According to the MSDS you should not expose PLA to temperatures over 120 degrees F. While the melting point of PLA is just over 300 degrees, the glassing point is much lower at 140 degrees. The glassing temperature is very important because that is a reversible point at which the plastic transitions from soft to hard when cooled, or from hard to soft when heated.
To put things into perspective lets consider the following link over at NOAA Heat Safety Resources and click on the section called “How Fast Can The Sun Heat A Car”.
The slideshow does a good job of illustrating that your cars interior can exceed the recommended storage temperature, and even the glassing temperature of PLA plastic. 3D printed PLA has proven to be very safe, reliable, and durable. Even able to withstand a lot of use and abuse, but everything has its limits. Exposure to excessive heat will damage your parts so it is very important that you take care and heed this warning.
Do not leave your 3D printed parts in the car. Your parts and your warranty depend on it!