Thank You for the article!!!
It is very helpful to understand the a) stiffness, b) impact strength, and c) comparison of different type of plastic.
As the article mentioned, there are many type of plastic. But how do you know what grade is your filament ??
For experts, they are able to distinguish by touch, visual, and the scent when burning the plastic.
For others, you can perform a small test on the filaments.
1) You can bend the filament back and forth until it breaks
2) feel the smoothness of the filament
Let me find out more tests you can perform on the filaments.
Happy Printing !!