Physical and water aging of glass-fibre reinforced plastic pipes

ARIEL STOCCHI; A.PELLICANO; J.P. ROSSI; C.BERNAL; P.E.MONTEMARTINI

Buenos Aires

Conferencia; III International Conference on Science and Technology of Composite Materials; 2005

Physical and water aging of glass/epoxy composite –GFRE–  pipes  used for oil transport were investigated with special emphasis on its effect on the flexural and impact behavior. Different aging conditions were selected in order to simulate in-service environments trying to obtain reliable results from accelerated laboratory tests. In water uptake experiments at 80ºC, the mass increases continuously suggesting that an irreversible process exists. In addition, samples aged in air at 80 ºC exhibit a DSC endothermic peak which can be related to physical aging. The calorimetric curve for specimens water aged at 80 ºC shows combined effects of water absorption and physical aging. On the other hand, while the independent effect of temperature and water aging on the composites mechanical response is only moderate, the combined effect of them seems to be dramatic. This result is mostly attributed to the weakening of the fiber-matrix interface induced by the water aging at high temperature, which consequently affect flexural and impact properties. SEM observations confirm the irreversible damage observed in water uptake experiments. Good interfacial adhesion between fiber glass and epoxy resin is observed for unaged specimens, whereas completely clean fibers are seen for specimens water aged at 80 ºC indicating that fiber-matrix interface is completely removed as a result of this aging condition.