Fecha de publicación: -- Fuente: Journal of applied polymer Lugar: RESEARCH ARTICLE Electrospun polysulfone interlayers with controlled MWCNT loadings create a hierarchical toughening architecture in epoxy. Combined changes in nanofiber morphology, interlayer content, and interfacial fracture mechanisms produce a maximum apparent fracture toughness of 5.08 ± 0.31 MPa m1/2 for EP1C15, a 96% increase over neat epoxy.

ABSTRACT
Epoxy-based nanocomposite laminates reinforced with electrospun polysulfone (PSU) nanofiber interlayers, with and without multi-walled carbon nanotubes (MWCNTs), were fabricated and evaluated under notched tensile loading. The study was structured around a systematic design matrix consisting of 13 material groups: neat epoxy and PSU nanofiber interlayer systems produced with 0, 1, 2, and 3 wt% MWCNT at 5, 10, and 15 interlayer counts, with five specimens prepared for each group. Fracture performance was compared using an apparent critical stress-intensity factor, Kapp$$ {K}_{\mathrm{app}} $$, calculated for a finite-width single-edge-notched strip under uniform tension. Both interlayer number and MWCNT content affected Kapp$$ {K}_{\mathrm{app}} $$. The highest value was obtained for the 15-layer laminate containing 1 wt% MWCNT, which reached 5.08±0.31$$ 5.08\pm 0.31 $$ MPa m1/2 and showed a 96% improvement over neat epoxy. Transmission electron microscopy (TEM) and scanning electron microscopy (SEM) observations linked the fracture-resistance trend to a structure–mechanism–property relationship involving nanotube dispersion, interlayer-mediated crack tortuosity, crack bridging, and interfacial wetting/debonding. Thermogravimetric analysis (TGA) and differential thermal analysis (DTA) showed higher residual mass for the reinforced laminates and an increase in glass-transition temperature with MWCNT addition.