Characterization of absorbed water in aramid fibre by nuclear magnetic resonance

While many studies have focused on the mechanical degradation of aramid/epoxy composites by water absorption, little work has been done to gain a deeper understanding of the interaction between absorbed water and aramid fibres. In this study, ¹³C, ¹H, and ²³Na 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 larger core defects. The absorbed water partially dissolves sodium salts, consisting mainly of sodium carbonate, which are present in the pores. No evidence of chemical breakdown of the aramid polymer, or of water ingress within the polymer lattice, was observed.