Preparation of Polyimide Nanofiber Membranes and Interlaminar Toughness Investigation of Their Toughened Composites.

Interlaminar delamination and brittle fracture of matrix have been a dilemma that fiber-reinforced composites have been faced with. Herein, the polyimide (PI) nanofiber-toughened glass fiber fiber-reinforced epoxy composites were prepared by electrospinning method and subsequent vacuum assistant resin transfer molding. The effect of spinning parameters including PI concentration, applied voltage, collector distance, jet speed and ambient humidity on the resultant fiber diameter and its distribution was systematically evaluated. The surface properties of obtained PI nanofibers were characterized by FT-IR, TG-DSC and water contact angle. The effect of PI concentration on tensile strength of PI membranes was also studied. The mode I (G Ic ) and mode II (G IIc ) interlaminar fracture toughness were measured. The results indicated that GIc and GIIc increased by 127.69% and 85.33%. The improvement of interlaminar fracture toughness may be attributed to the bridging effect of PI nanofibers. Preparation and parameter optimization of polyimide nanofiber membranes was made by electrospinning method. Then the polyimide nanofiber membranes were utilized as the toughening layer to improve the interfacial properties of fiber reinforced composites. The fracture surface was observed, and the toughened mechanism was discussed. [ABSTRACT FROM AUTHOR]