Poor interfacial properties are always one of the bottleneck problems limiting the development of the PBO fiber/epoxy composites. To solve this, we demonstrated a mussel-inspired molecular regulation strategy of interphase structure using the layer-by-layer construction of rigid (PDA) and flexible (PEI) molecules without fiber structure damage. The precise control on the molecular scale can maximally increase the roughness and polar functional group on the fiber surface, thus enhance the chemical bonding and the mechanical interlocking of the interfacial adhesion. In comparison with the untreated fiber, the IFSS and ILSS value of fiber with (PDA/PEI)n have an increment of 86.85% and 80.08%, respectively. Besides, the overall mechanical performance, such as impact strength and dynamic thermal-mechanical behavior, was also improved significantly, owing to the improved physical-mechanical attributes of the interphase. In brief, our study presents a non-destructive interface regulation of PBO fiber composite to enhance its interfacial adhesion and mechanical performance and optimize its structure/function integrated design.
The liable interfacial delamination of carbon fiber composites is a long-lasting problem that restricts its widely application. One promising route is to hybridize fiber with nano-particles on account of their prominent mechanical properties and huge specific surface area, while trial using biobased nanoparticles are in its infancy. Mussel adhered firmly to the reef relies on its bushy byssal threads, which correlates with chelation of ferric ions with catechol-containing proteins. Inspired by this, we deposited synergistic bio-based polydopamine (PDA)-Fe complex nanospheres and silane coupling agent on carbon fiber by simply impregnation, which delivers increment of 56.4% in interfacial shear strength (IFSS) in epoxy matrix relative to untreated fiber composites . Results suggest that the improved epoxy wetting behavior that imparts full infiltration, the excellent adhesivity that eliminates weak interface layer , as well as strong but reversible PDA-Fe chelate crosslinks that advance tress transfer and energy dissipation , which are critical to IFSS growth. This work provides a new and attractive bio-nanomaterial of PDA-Fe in interfacial engineering of composites.
A self-synthesized octa(γ-chloropropyl) polyhedral oligomeric silsesquioxanes (POSS) and its evolutionary amino-terminated hyperbranched structure were introduced onto the carbon fibers (CFs) surface (CF-G n -POSS-NH 2 , n = 1, 2 and 3) by chemically and successively grafting method to improve the interfacial properties of CFs/epoxy composite. The fiber surface structures could be tuned through regulating grafting generation ( n ) of CF-G n -POSS-NH 2 , and the polarity and roughness of CF surface increased with the incremental dendritic generation number. Interfacial shear strength (IFSS), interlaminar shear strength (ILSS) and dynamic mechanical properties of the functionalized CFs composites improved as the grafting generation increased, which may be attributed to the varying degrees of chemical interaction, mechanical interlocking and resin wettability provided by hyperbranched G n -POSS-NH 2 interface. Moreover, the interfacial structure has been also speculated and analyzed.
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