The interfacial feature of thermoplastic polystyrene composite filled with nitric acid oxidized carbon fiber

Thermoplastics Reinforced with Self-Welded Short Carbon Fibers: Nanoparticle-Promoted Structural Evolution

The large volume of currently available fiber-reinforced polymer composites critically limits the intrinsic versatility of fibers such as high mechanical strength, heat resistance, and excellent thermal/electrical conductivity. We proposed a facile and widely applicable strategy to promote self-organization of randomly dispersed short carbon fibers (CFs) into a three-dimensionally continuous scaffold. The morphological evolution and structural reinforcement of the self-welded CF-polyamide 6 (PA6) scaffold in polystyrene (PS) matrix were investigated, with carbon black (CB) or titanium dioxide (TiO2) nanoparticles (NPs) selectively localized in the PA6 domains. Surprisingly, all of the PA6 droplets once dispersed in the PS matrix can migrate and evenly encapsulate onto the CF surface when 5.8 wt % CB is incorporated, whereas in the TiO2-filled system, the PA6 droplets preferentially segregate at the junction point of CFs to fasten the self-welded CF structure. In addition, a remarkable increase in the interfacial adhesive work between PA6 and CF was observed only when TiO2 is added, and a loading of even less than 0.8 wt % can effectively abruptly strengthen the self-welded CF scaffold. We clarified that the structural evolution is promoted by the nature of self-agglomeration of NPs. CB is highly capable of self-networking in the PA6 domain, resulting in high encapsulation of PA6, although the capillary force for preferential segregation of PA6 at the junction point of CFs is reduced. By contrast, the TiO2 particles tend to form compact aggregates. Such an agglomeration pattern, together with enhanced interfacial affinity, must contribute to a strong capillary force for the preferential segregation of PA6.

Effect of carbon fiber surface modification on the flexural mechanical properties of carbon fiber reinforced polyetheretherketone biocomposites

Carbon fiber (CF) reinforced polyetheretherketone (PEEK) is one of the most promising orthopedic implant biomaterials. In this paper, CF reinforced PEEK biocomposites were fabricated by hot press molding technology. The influence of the CF surface modification on the flexural mechanical properties of CF/PEEK biocomposites was investigated. Studies on the flexural mechanical properties of CF/PEEK biocomposites revealed that the flexural stress-strain behavior of the biocomposites possessed linear elastic characteristics. The fracture mechanism of the biocomposites was predominated by brittle rupture. Both flexural strength and modulus of the biocomposites obviously increased with the rise of CF content. The influence degree of different CF modification on the flexural properties of CF/PEEK biocomposites increased with the rise of CF content. Moreover, the CF modified by concentrated HNO3 is beneficial for the flexural strength of the CF/PEEK biocomposites improvement. Conversely, CF modified by KH-560 coupling agent played an adverse influence on the flexural strength of the biocomposites.