We believe that moisture may play a role in the aging of the polyamide networks, since amide bonds are hydrophilic (Figure ). For example, Nylon 66 can absorb 2-3 wt% water in 50% relative humidity air. When the meta-phthalamide/EBMP-TEMPIC (f=2.25) was placed in water for 72 hours, it gained 1.8 wt%.