Hi guys,
I’m trying to diagnose problems with a 55 ply (1/2" thk) 350°f cyanate ester/4581 AQIII Ø12"cylindrical pressure radome. The problem is that the laminate is not vacuum tight from the interior or externally tight at 870 psi (hydrostatic). Item is debulked every 2 plys and finally cured in clave at 50 psig per mfg temp profile. Laminate exhibits dark lines and dark splotchy areas that are from 1 to 20 plys deep. Microscope shows suspended voids and resin rich areas. I cannot trace the leak as its probably a worm path. Any ideas on alternate processing? (Note that this is ~$8,000 of material.)
Thanks…
Check to see if the prepregger coated it well. If the single layer resin ratio is off here and there, it might not flow well. Also, make sure your bagging is per spec (release (perf or not), capillary tows for VOC venting, etc. I know our tencate BTCY-1 with S2 (7781) is resin rich like crazy, and will look funky without bleeding. Last few panels I’ve done look great with perf release, and one layer of airweave on top.
Now, voids might be an issue with moisture uptake in the resin. Is the roll stored correctly? Has it been sitting out ready to layup for a few weeks? Maybe sit the autoclave at a low temp (120ish) for a bit to draw out any moisture. Slow ramp, soak, and cooldown.
Very odd that you are seeing worm paths for 1/2" thick lam!!! it might be a good idea to cure half a a time, to seal in any void paths?