Polyetherimide nanofiber membranes imultaneously enhance interlaminar toughness and in-plane mechanical properties of CF/EP composites prepared by VARI process

This study investigates the influence and underlying microstructural mechanisms of electrospun polyetherimide (PEI) nanofiber membranes on the interlaminar toughness and in-plane mechanical properties of vacuum-assisted resin infusion (VARI) process molded carbon fiber/epoxy (CF/EP) composites. It is founded that PEI nanofiber membranes exhibit good wettability with epoxy resin and do not impede resin flow. PEI nanofiber membranes are suitable for the VARI process under the conditions of a 70 degrees C resin infusion temperature and infusion time less than 30 min. Furthermore, they are dissolved completely within 6 minutes at the resin curing temperature of 120 degrees C . Incorporation of PEI nanofiber membranes enhances the interlaminar toughness and in-plane mechanical properties of CF/EP composites. Interleaving 15 g/m(2) PEI nanofiber membrane in CF/EP composites increases the mode I interlaminar fracture toughness, mode II interlaminar fracture toughness, and interlaminar shear strength by 55. 1%, 65. 4%, and 12. 2%, respectively. Introducting a 20 g/m(2) PEI nanofiber membrane in CF/EP composites enhances the flexural strength and modulus by 10. 6% and 9. 3% , respectively. Moreover, adopting a 10 g/m(2) PEI nanofiber membrane enhances the compression strength and modulus of CF/EP composites by 24. 3% and 18. 9%, respectively. The in-situ dissolution of PEI nanofiber membranes and the reaction induce phase separation during epoxy resin curing lead to a homogeneous PEI/epoxy resin bi-phase structure in the interlaminar region of CF/EP composites. These structures enhance the resistance to crack propagation and the load transfer capability of the interlaminar resin matrix, probably improvement in interlaminar toughness and in-plane mechanical properties of CF/EP composites.