Does storing fabric in a non humidity controled environment cause permanent negative effects?
I know fiberglass is sensitive to high moisture. cloths in general make better parts if you store them in as dry a climate as possible. You can a reaction from the moisture content that cloth absorbs from the air. I am in Phoenix AZ so this isn’t an issue for me as we have very dry air here.
I recently saw that consumers can buy a dehumidifier that will control the moisture in a room.
Should material that has seen high humidity be tossed?
I really do not know if high humidity affects the fiber or the sizing on the fiber.
Some sizings are starch based, so I guess there is an effect. However, if it is reversible, I do not know.
Long, long time ago we stored materials in an old shed. Sometimes the rain came through, and wetted a couple of rolls of glass. Our neighbour was a producer of firebricks, so we placed the rolls of glass as near to the oven as we could (oven at 1500 degrees C). This effectively dried the rolls, and subsequent processing did not see anything unusual. However, the products were low-tech.
Problems you can expect with high humidity:
-polyester: lower final cure, gas formation, porosity
-epoxy: gas formation, faster cure, porosity
-PU: do not try. PU and water are real enemies.
-Phenolics: no experience.
Whether or not I should add bad adhesion, worse ILSS, etc, I do not know, but I do expect effects.
Also I have been told, but not from own experience, that Vf is affected. Dry fabrics use less resin.
With infusion you can see that you will not reach less than 20 mbar or so. This is the boiling point of water at RT. Only when all the water has flashed off, the pressure drops again. It is desireable to flash off all the water. (to avoid gas formation)
Aramid/Kevlar and other polyamid materials are hygroskopic. Glas will not make problems if stored in a normal dry room, also carbon will not cause any problems.
Aromatic polyamides like Kevlar7Aramid… have to be dryed in the vacuum before using them.