Solvents Aging of Composites Used for Oil Transport

VICTORIA RAMOS; DAMIÁN GUIDO; CELINA BERNAL; PABLO MONTEMARTINI

Buenos Aires

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

This work deals with the influence of organic solvents on GFRP behaviour. Preliminary results of weight change as a function of aging time shown that a completely different behaviour of the GFRP aged in different solvents can be observed. While samples aged in CHX, NHX and AIP show a slightly decrease in their weight, those aged in benzene increase their weight during the analysed period. Moreover, CHX, NHX and AIP diffusion seem to reach a constant weight after 1500 h. On the other hand, BEN diffusion swells GFRP samples increasing not only the weight (0.8%) but also the volume (10%) of the samples after 6 month of aging. Dynamic-mechanical analysis results of samples aged during 6 months and the initial condition indicate that all four sets of aged specimens show a transition observed by a tan δ peak close to 140ºC in accordance with the result obtained for samples without aging. Besides the main transition, a second peak and a shoulder of the main peak can be seen in BEN and IPA aged samples respectively. BEN diffusion swells the epoxy producing a low glass transition temperature domain (aproximately 35°C). This fact results critical in service. The swelling due to low molecular weight aromatic species can be responsible for the Tg decreasing usually observed after failure. In service temperature range (40 – 80°C), mechanical deterioration observed in BEN aged samples decrease the storage modulus by a factor of 10. This behavior is also in agreement with failure analysis results obtained from oil transport pipes. Matrix degradation can be also observed by SEM images. After 6 month of aging in BEN, fiber debonding can be seen at the inner surface, where no liner exists.