Relationship between the moisture absorption and properties of carbon fiber filament-wound NOL rings

An accelerated aging method to characterize the hygrothermal properties of carbon fiber (CF) filament-wound composite pressure vessels in storage and service process was presented based on filament-wound composite NOL rings. The hygrothermal aging behavior of the CF/epoxy NOL rings in distilled water at 35℃，55℃，65℃ and 75℃ was analyzed in terms of the absorption characteristics，static and dynamic mechanical properties. The CF/epoxy NOL rings display a three-stage absorption process，which is controlled in turn by diffusion in free volume，molecular relaxation and interface degradation. When the moisture content reaches about 1wt%，the ring shear strength and flexural strength decrease to 75% and 67%；meanwhile，the Tg decreases by 20℃. The results providea good basis for the prediction and estimation of the storage life of carbon fiber filament-wound composite pressure vessels.