Uh, ben, I don't think that's why we don't use teflon tape. If applied properly, in the right direction and using the proper amount, teflon tape will seal ANY fitting... that's the whole point why we have the stuff. Again, we are concerned about stresses that cause crack propagation, not leaks that are caused by water traveling along the thread! Sealants aren't supposed to bond, they are supposed to fill microvoids and thereby keep water from getting through
Cova, there are polycarb barbs, you can find them at
www.mcmaster.com ... using a chloride based forula to fuse the two together would be nice... however as BillaA said, why not use polycarbonate tube that is inserted and fused in. Let me go find the proper mcmaster pages!
Also... I have done extensive studies on crack propagation in metals, and the point BillA made about temperature having a big impact is valid for metals. However, I hate to point out the fact that the minute (say + or - 15degrees K) temperature fluxuations in this application will not promote, speed up, slow down, or hinder any sort of crack propagation in polycarbonate plastics... the ductile to brittle transition temerature for polycarbonate lies far below any temperature your block will ever experience... a big NOT goes out to BillA hence. To proove me wrong, please provide me with a datasheet on Lexan specifying the exact DBTT and also how in the world any environment inside a computer could possibly reach this temperature.
OK. Edit: See page 114 in McMaster for polycarb host fittings!