Boosting interfacial adhesion in PBO fiber/epoxy composite by employing finely granular-structured polyaniline as an interfacial intensifier

Poor interfacial adhesion of composites deriving from the surface smoothness and inertness of poly (p-phenylene benzobisoxazole) (PBO) fibers severely constrains the extensive application of the fillers. Constructing the functional coating is generally considered a non-destructive and scalable strategy to simultaneously improve the asperity and activity of PBO fiber surfaces. Herein, we report a facile method to boost the interfacial adhesion in PBO fiber/epoxy composite by employing finely granular-structured polyaniline (PANI) as an interfacial intensifier. Via a mild and efficient in situ polymerization technique, the positively charged micron-scale PANI particles are uniformly anchored onto the negatively charged PBO fibers to form delicate leather-like surface layer containing substantial amino groups. Meanwhile, the resulting PBO fibers maintain excellent mechanical properties. Therefore, the PANI-coated PBO fiber/epoxy composite ([email protected]/EP) shows the significant increase in interfacial shear strength (41.0 MPa) and interlaminar shear strength (44.9 MPa), soaring by 60.16 % and 54.83 %, respectively. The debonding behavior and fracture surfaces confirm that the interfacial failure mechanism of [email protected]/EP converts from adhesive failure to both cohesive and substrate failure. The strategy in this work to modify PBO fiber surfaces for increasing the interfacial combination of composite is cost-effective and feasible to scale up.