I flaired as “other,” but I suspect this involves both chemistry due to state of matter changes and physics due to the involvement of thermodynamics. I don’t know. If you want to tell me with your answer which flair would’ve been more appropriate, I’d appreciate it.
I’ve tried looking up injection molding, since I assume it’s similar (although it seems the processes I’m reading about require a more solid resin than the “Goop” you used in these toy molds). Even though the Goop isn’t quite solid, I’m assuming the process is still that it melts down even more and then becomes more solid during the cooling process.
I’m just not understanding why. I might understand if it had started solid, since then cooling it just returns it to its natural state after heating. That would just be like making fudge. But this stuff was gooey, and it came out firmer (although still pretty wobbly) after you cooked and cooled it. How would you explain the science of how this works in child-friendly terms? How does reducing a goo into liquid and then cooling it make it firmer?
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So, chemistry is a complicated thing. Sometimes two compounds react when they touch each other. This can result in all kinds of chemical reactions. Sometimes they make air. Sometimes they make heat. Sometimes they get harder. Sometimes they get softer. Sometimes they attach what they’re touching when they harden.
The main ingredient in creepy crawler goop was PVC, or a kind of plastic. Lots of plastic that looks and acts different is also PVC, so PVC can be a wide range of things. Lots of plastic gets harder when you heat it up — that was the first way we started making shapes out of plastic. That’s why a lot of cheaper plastic things have a seam on the sides of them! That means they were once a liquid, poured into a mold into the shape of the thing someone wanted, and then heated up. Once it cools, it stays solid! More expensive things can also be made this way — they just try to file or treat the seam so it isn’t as obvious.
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