Four types of fabrics woven from various polyaramid fibers of Nomex and Kevlar blends were characterized by morphology, XRD, elemental analysis, thermal analysis, and moisture adsorption isotherms. The blends consisted of Polybenzimidazole/Kevlar blend (40% PBI and 60% Kevlar (R)), Nomex Delta A (blend of 60% Kevlar and 40% Nomex (R)), Nomex Delta T (blend of 75% Nomex, 23% Kevlar, and 2% P140 antistatic fiber), and Nomex III (fabric with a 95/5 blend of Nomex and Kevlar) containing 1% steel fiber. TGA and DTG curves have been compared to evaluate thermal behavior of the PBI, Kevlar, and Nomex blends and the resuls were correlated with the moisture sorption data. The data were also compared with fiber morphologies provided by SEM and crystallinities derived from XRD diffractograms. Moisture adsorption isotherms were correlated with a number of empirical models, including Nernst, Freundlich, Handersen, Iglesias-Chirife, and with the models having a theoretical background such as Langmuir, BET, GAB, and Huttig. The linear regression models were statistically analyzed to obtain the best fitting model that explains the sorption profiles of the samples and theoretical monolayer moisture capacities of Nomex and Kevlar blends were calculated by using Huttig isotherms. (c) 2006 Wiley Periodicals, Inc.