Dynamic viscoelasticities of CF/GF hybrid reinforced epoxy composites under high load

The EPLEXOR 500 was used to investigate the dynamic viscoelasticities of T300/S-2 hybrid reinforced epoxy composites. The effects of the static load and dynamic load on the storage modulus, loss modulus and loss tangent of hybrid composites were studied. The effects of hybrid ratios and hybrid modes on dynamic viscoelasticities under different load levels were discussed and compared. The results show that the storage modulus of the composites with different hybrid ratios uniformly decreases with the increase of dynamic load and increases with the increase of static load. The loss modulus and loss tangent both decrease with the increase of the static or dynamic loads. The storage modulus of the hybrid composites under high load approximately conforms to the Composite Beam Theory. In the dynamic load sweep mode, the variation of loss tangent with the volume fraction of carbon fiber can still be described by the Mixture Rule, and the storage modulus of sandwich hybrid composites is much higher than that of interlaminar hybrid composites. In such sweep mode the loss tangent of sandwich hybrid compo-sites is also larger than that of interlaminar hybrid composites, but in the static load sweep mode, the case is reverse.