From the loctite web site. It doesn't mention whether it will damage plastics but it does say it is not effective for locking plastic threads

http://www.loctiteproducts.com/quest...rme=124#cat124

Question
I used Threadlocker on a metal bolt and a plastic nut. Why didn't it stick?

Answer
Threadlockers should only be used on metal-to-metal applications, because the Threadlocker turns into a plastic-like substance.