Polymers
Many engineering polymers are hygroscopic. These include: nylon, ABS, polycarbonate, cellulose, and Poly(methyl methacrylate).
Other polymers, such as polyethylene and polystyrene, do not normally adsorb much moisture, but are able to carry significant moisture on their surface when exposed to liquid water.
Type-6 nylon can absorb up to 9.5% of its weight in moisture.
Read more about this topic: Hygroscopy