Aside from dissecting the belt, I wouldn't know how to know if there was plastic in it.
I've only worn it a few times, haven't even tried to lift any weight while wearing it, but bracing against it just doesn't feel like anything. Like I said, it feels like I'm not wearing a belt. If you want to spend money on a belt just to have a belt, it will definitely be something you can spend money on. For the cost, I'd get the spud deadlifting belt, which I was also not very impressed with, but it DOES feel like more support than the elitefts one. I've used the spud for log clean and press, and it did a decent job.
EDIT: Also, If I were you, I'd listen to CParker and get the belt he is talking about. $50 is cheap, and CParker is ridiculously strong. His word holds weight.