Establishment of multi-scale interface in interlayer-toughened CFRP composites by self-assembled PA-MWNTs-EP

A pelote-like hybrid particle was fabricated via self-assembly of PA microparticles and epoxy functionalized carbon nanotubes (MWNTs-EP), and the effects of interlayer films containing self-assembled hybrid particles (PA-MWNTs-EP) on interlaminar shear property and fracture toughness of CFRP composites were studied. The spontaneous self-assembly was ascribed to electrostatic adsorption between MWNTs-EP and PA microparticles. Remarkable improvements in interlaminar shear strength (ILSS) and mode I fracture toughness (GIC) of the CFRP composites were achieved with the incorporation of interlayer films containing PA-MWNTs-EP. The pelote-like microscopic structure of PA-MWNTs-EP was considered to provide extraordinary synergy of one-dimensional MWNTs-EP and three-dimensional PA microparticles through establishment of multi-scale interface based on chemical bonding. A schematic model of stress transfer was proposed to illustrate the effects of multi-scale interface established among PA, MWNTs-EP, epoxy matrix, and carbon fiber in the interlaminar region of interlayer-toughened CFRP composites.