Improvement of Dispersibility of Graphene Oxide by Surface Modification with Rare Earths

Rare earth-modified graphene oxide (RE-M-GO) materials were successfully prepared by infiltration and heating modifier method. The morphology and phase structure of RE-M-GO were characterized by scanning electron microscopy(SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and energy dispersive spectrometer(EDS). The changes of the chemical structure were indicated by Fourier transform infrared (FTIR). X-ray photoelectron spectroscopy(XPS) was used to study the chemical state of the surface elements of graphene oxide which showed that the rare earth elements were added to the graphene oxide functional groups through the coordination reaction. Additionally, the findings concluded that the effect of modification by Ce is more obvious than La elements and the RE-M-GO materials prepared by the heating modifier method had better dispersibility than infiltration. With activating effect, the rare earth elements grafting to graphene oxide will contribute to its combination with other materials.

Improved interfacial performance of carbon fiber/polyetherimide composites by polyetherimide and modified graphene oxide complex emulsion type sizing agent

In the field of interfacial enhancement of composite, sizing method has attracted extensive attention. In this research, a new complex emulsion type sizing agent containing polyetherimide (PEI) and covalently chemical functionalized graphene oxide (GO) was first proposed to further improve the interfacial adhesion of carbon fiber (CF)/PEI composites, adapt to the high processing temperature, and overcome the shortcomings of the solution type sizing agent. The emulsion was prepared by the emulsion/solvent evaporation method. In order to avoid the agglomeration of nanomaterials on CF surface, the monomer and polymer structure of PEI was used to functionalize GO, so as to achieve better compatibility and dispersion of GO in PEI. The physicochemical state of CF surface was characterized and the successful introduction of GO was verified. The microbond test revealed that the introduction of GO further improved the IFSS compared with only PEI sizing. When GO grafted with PEI was used as the main component of the sizing agent, the IFSS reached the largest with an increasement of 55.96%. The mechanism of interfacial reinforcement was proposed. Increased ability of mechanical interlocking, the mutual solubility between PEI molecular chains, and the improvement in wettability may be beneficial to the interfacial strength. This mild and effective modification method provided theoretical guidance for the interfacial enhancement of composites and was expected to be applied in industrial production.

Enhanced Performance of PVDF Composite Ultrafiltration Membrane via Degradation of Collagen-Modified Graphene Oxide

The collagen obtained from chrome leather waste can be used to modify graphene oxide (GO) to prepare polyvinylidene fluoride (PVDF) composite ultrafiltration membranes, a process that is conducive to the recovery of leather waste, comprehensive utilization of GO and improved performance of the membrane. In this paper, collagen-modified GO (CGO) was prepared by degradation of collagen from chrome leather waste and used to prepare a PVDF composite ultrafiltration membrane. The results show that the carboxyl content of CGO and dispersion were improved. The water flux and flux recovery rate of the modified ultrafiltration membrane were improved. The bovine serum albumin (BSA) intercepted on the membrane surface was easy to clean and the antifouling performance improved. The performance of the membrane decreased when the GO content exceeded 0.75 wt%, while CGO can reach 1.0 wt% without agglomeration due to its good dispersion.