I recently(ish) got a used splitboard: a Jones explorer. The clamp system that held the two halves of the split board together was held in place with a nut and bolt that was free spinning without loosening. The nut had a little white plastic sleeve in it. Turns out it's called a nyloc nut.
The plastic sleeve is threaded, but it's ever-so-slightly different from metal's thread. When you fasten the bolt in, the plastic threads deform and grip the bolt, acting like a loctite and stopping the bolt from shaking loose.
That's pretty genius, and I've checked the clamps on my splitboard and in around 10~ days out they've not backed out at all.
The nyloc nut is a wear part, even though I can see it probably lasting for a long time in this application, there is stress on plastic threads. With enough adjusting, exposure to UV and freeze thaw the tightness of the nyloc would definitely be impacted.