Effect of carbon nanofibers on the viscoelastic response of carbon/epoxy composites

Carbon fibre reinforced polymer (CFRP) laminates nano-enhanced with carbon nanofibers (CNFs): 0.75 wt% and 0.5 wt% of epoxies Sicomin and Ebalta, respectively, were manufactured and their static and viscoelastic behaviour analyzed. After 180 min, the bending stress decreases and creep displacement increases over time, with Ebalta nano-enhanced resin laminates with CNFs showing the best results. A strong dependence of creep behaviour and stress relaxation is obtained with the applied stress level. The results show that laminates produced with pure Sicomin resin increased creep displacement by 1%, for a bending stress of 200 MPa, and 2 times greater for the bending stress of 700 MPa. The viscoelastic behaviour of CFRP composites nano-enhanced with CNFs was accurately predicted by the Kohlrausch-Williams-Watts (KWW) model and Findley power law.