抄録
The sorption behavior of water vapor on wholly aromatic polyamides (Aramides) such as Kevlar 29, Kevlar 49 and Nomex, was investigated, and was compared with that on aliphatic and alicyclic polyamides. The amount of water adsorbed in a monolayer state (vm) was estimated by BET plot for each sample. The ratios of vm to the concentrations of amide groups in amorphous region (vm/18[CONH] (1-α). α; crystallinity), which correspond to the effective number of sorption site for water per amide group in amorphous region, decreased in the following orders; Nomex>Kevlar 29>Nylon 6>Monece>Poly 12 HHTPA for fibers, and Nomex>Kevlar 29>Nylon 2>Nylon 3>Nylon 4>Nylon 6>Poly 12 HHTPA for powder samples. From the analysis using the cluster functions, it was elucidated that the moisture regain at which the water clusters began to arise was somewhat larger than the vm for all the samples. On the other hand, the half-height widths in 1H NMR spectra of adsorbed water in Aramides were narrower than those in other polymers at the same moisture regain. It seems, therefore, that in Aramides the fraction of water molecules tightly bound to amide groups is smaller than that in the other polymers.
