Vitrimer carbon fiber composites for rotorcrafts components with fatigue reversal ability

As rotorcrafts enter new generation of their design, they are expected to be subjected to more stringent performance requirement, Increased loads and operational frequency necessitates use of structural components with higher fatigue life. Carbon fiber reinforced polymer composites (CFRP) are popular as structural material due to their superior performance while being lightweight. However, fatigue originating in weaker polymer limits their fatigue life, moreover the fatigue damage introduced accumulated irreversibly resulting in catastrophic failure. The damage is irreversible due to permanent crosslinked nature of thermoset polymers used in CFRP. If the crosslinks are made dynamic i.e. reversibly crosslinked, the fatigue damage may be reversed imparting ultra-high fatigue life to the components. Vitrimers are such epoxy based networks which may be ideal candidate for this application as they possess ability to dynamic crosslinking at elevated characteristic temperature. Here we report a vitrimer based CFRP i..e., vCFRP which has properties comparable to conventional CFRP which has ability to retain its original properties in fatigue tests when they are subjected to periodic heating. The fractographic analysis suggests that periodic heating serves dual purpose of enabling dynamic crosslinking as well as repairing small scale fiber-matrix interface failure. Thus, rotorcraft components made with vCFRP may have very high fatigue life compared to conventional CFRP components.