The functional groups on graphene sheets surface affect their dispersion and interfacial adhesion in polymer matrix. We compared the mechanical property of polymethymethacrylate（PMMA） microcellular foams reinforced ...The functional groups on graphene sheets surface affect their dispersion and interfacial adhesion in polymer matrix. We compared the mechanical property of polymethymethacrylate（PMMA） microcellular foams reinforced with graphene oxide（GO） and reduced graphene oxide（RGO） to investigate this influence of functional groups. RGO sheets were fabricated by solvent thermal reduction in DMF medium. UV-Vis, FT-IR and XPS analyses indicate the difference of oxygen-containing groups on GO and RGO sheets surface. The observation of SEM illustrates that the addition of a smaller number of GO or RGO sheets causes a fine cellular structure of PMMA foams with a higher cell density(about 1011 cells/cm3) and smaller cell sizes（about 1-2 μm） owing to their remarkable heterogeneous nucleation effect. Compared to GO reinforced foams, the RGO/PMMA foams own lower cell density and bigger cell size in their microstructure, and their compressive strength is lower even when the reinforcement contents are the same and the foam bulk density is higher. These results indicate that the oxygen-containing groups on GO sheets’ surface are beneficial to adhere CO2 to realize a larger nucleation rate, and their strong interaction with PMMA matrix improves the mechanical property of PMMA foams.展开更多
The electroless nickel plated graphite fibers reinforced aluminum matrix composites (Gr(Ni))/Al) were produced by squeeze casting, and the microstructure of Gr(Ni)/Al composite and surface behavior of Ni-P coating wer...The electroless nickel plated graphite fibers reinforced aluminum matrix composites (Gr(Ni))/Al) were produced by squeeze casting, and the microstructure of Gr(Ni)/Al composite and surface behavior of Ni-P coating were studied. The optimum process of electroless Ni-P plating included: burning to get rid of glue→degreasing→neutralization→acidulating→sensitizing→activation→electroless plating. The surface analysis results show that the electroless nickel plating can diffuse into the graphite fiber surface during the squeeze casting, and the Ni-P coating and aluminum alloys can produce brittle phase NiAl3 or NiAl. The X-ray diffraction(XRD) results indicate that Al4C3 is so little that no Al4C3 peaks are found, and the harmful Al4C3 can be decreased by the electroless plating Ni-P coating. The coating improves the interfacial bonding of continuous graphite fibers reinforced aluminum matrix composites.展开更多
The chemical composition obviously affects the surface wettability of a three-dimensional(3D)graphene material apart from its surface energy and microstructure.In the hydrothermal preparation,the heteroatom doping cha...The chemical composition obviously affects the surface wettability of a three-dimensional(3D)graphene material apart from its surface energy and microstructure.In the hydrothermal preparation,the heteroatom doping changes the chemical composition and wettability of the 3D graphene material.To realize the controllable surface wettability of graphene materials,aminobenzene sulfonic acid(ABSA)was selected as a typical doping agent for the preparation of nitrogen and sulfur co-doped 3D graphene foam(SNGF)using a hydrothermal method.Different from using o-ABSA or p-ABSA as the dopant,SNGF with tunable surface wettability is obtained only when m-ABSA is used.This result indicates that the substituent position of-SO3H group in the benzene ring of ABSA is rather important for the tunable wettability.This work provides some theo retical foundations for dopant selection and some new insights in manipulating the properties of 3D graphene foams by adjusting the configuration of dopants.展开更多
基金Funded by the National Nature Science Foundation of China(No.51521001)
文摘The functional groups on graphene sheets surface affect their dispersion and interfacial adhesion in polymer matrix. We compared the mechanical property of polymethymethacrylate（PMMA） microcellular foams reinforced with graphene oxide（GO） and reduced graphene oxide（RGO） to investigate this influence of functional groups. RGO sheets were fabricated by solvent thermal reduction in DMF medium. UV-Vis, FT-IR and XPS analyses indicate the difference of oxygen-containing groups on GO and RGO sheets surface. The observation of SEM illustrates that the addition of a smaller number of GO or RGO sheets causes a fine cellular structure of PMMA foams with a higher cell density(about 1011 cells/cm3) and smaller cell sizes（about 1-2 μm） owing to their remarkable heterogeneous nucleation effect. Compared to GO reinforced foams, the RGO/PMMA foams own lower cell density and bigger cell size in their microstructure, and their compressive strength is lower even when the reinforcement contents are the same and the foam bulk density is higher. These results indicate that the oxygen-containing groups on GO sheets’ surface are beneficial to adhere CO2 to realize a larger nucleation rate, and their strong interaction with PMMA matrix improves the mechanical property of PMMA foams.
文摘The electroless nickel plated graphite fibers reinforced aluminum matrix composites (Gr(Ni))/Al) were produced by squeeze casting, and the microstructure of Gr(Ni)/Al composite and surface behavior of Ni-P coating were studied. The optimum process of electroless Ni-P plating included: burning to get rid of glue→degreasing→neutralization→acidulating→sensitizing→activation→electroless plating. The surface analysis results show that the electroless nickel plating can diffuse into the graphite fiber surface during the squeeze casting, and the Ni-P coating and aluminum alloys can produce brittle phase NiAl3 or NiAl. The X-ray diffraction(XRD) results indicate that Al4C3 is so little that no Al4C3 peaks are found, and the harmful Al4C3 can be decreased by the electroless plating Ni-P coating. The coating improves the interfacial bonding of continuous graphite fibers reinforced aluminum matrix composites.
基金the National Natural Science Foundation of China(No.21675133)。
文摘The chemical composition obviously affects the surface wettability of a three-dimensional(3D)graphene material apart from its surface energy and microstructure.In the hydrothermal preparation,the heteroatom doping changes the chemical composition and wettability of the 3D graphene material.To realize the controllable surface wettability of graphene materials,aminobenzene sulfonic acid(ABSA)was selected as a typical doping agent for the preparation of nitrogen and sulfur co-doped 3D graphene foam(SNGF)using a hydrothermal method.Different from using o-ABSA or p-ABSA as the dopant,SNGF with tunable surface wettability is obtained only when m-ABSA is used.This result indicates that the substituent position of-SO3H group in the benzene ring of ABSA is rather important for the tunable wettability.This work provides some theo retical foundations for dopant selection and some new insights in manipulating the properties of 3D graphene foams by adjusting the configuration of dopants.
