So I see lots of questions about foam, particularly confusion and conjecture about the different types of foam out there. I am no expert, but as an engineer and scientist, I decided to do my homework on the topic, and post up my findings to maybe help people understand the differences.

Most everything I will post up is from fact-based websites like wikipedia and the like. I'll try and cite sources where I can.

The Basics
In order to make foam, you start with a plastic polymer of some sort, and "expand it". (The "E" at the beginning of "EPO" and "EPP" always stands for "Expanded") You start off with a dense plastic resin material, mix it with a catalyst and it fills with millions of tiny gas bubbles while expanding to several hundreds of times its original size. If you think about how a popcorn kernel expands out into popcorn when heated, you're not far from the mark.

Now the real key between the different types of foam is the base polymer expanded.



More to come.