Hi Christel - have you tried talking to “Loctite” themselves.
Through their website, I lodged and enquiry, and had a very helpful
and knowledgeable technician on the phone to me within 30 minutes!
Couldn’t believe it!! Might be worth a try, here’s their url
Back in my water rocket building days, the only adhesive that would
work for PET plastics (2 liter coke bottles) was a construction
adhesive called “PL PREMIUM.” This stuff sticks to just about
anything amd was able to withstand pressures of 100+ PSI. PET is
polyethylene terephthalate (basically polyester).
It’s available at hardware stores such as home depot.