CHARACTERIZATION OF ABSORBED WATER IN ARAMID FIBER BY NUCLEAR-MAGNETIC-RESONANCE

While many studies have focused on the mechanical degradation of arami d/epoxy composites by water absorption, little work has been done to g ain a deeper understanding of the interaction between absorbed water a nd aramid fibres. In this study, C-13, H-1, and Na-23 nuclear magnetic resonance was used to show that the absorbed water in Twaron fibre is located in small pores in the skin region of the fibres, and in large r core defects. The absorbed water partially dissolves sodium salts, c onsisting mainly of sodium carbonate, which are present in the pores. No evidence of chemical breakdown of the aramid polymer, or of water i ngress within the polymer lattice, was observed.