Jiaoxia Zhang

Strengthened epoxy resin with hyperbranched polyamine-ester anchored graphene oxide via novel phase transfer approach

AbstractThis work investigated the mechanical properties of epoxy resin composites embedded with graphene oxide (GO) using a novel two-phase extraction method. The graphene oxide from water phase was transferred into epoxy resin forming homogeneous suspension. Hyperbranched polyamine-ester (HBPE) anchored graphene oxide (GOHBPE) was prepared by modifying GO with HBPE using a neutralization reaction. Fourier transform-infrared spectroscopy (FTIR), Raman spectroscopy, X-ray diffraction (XRD), and transmission electron microscopy (TEM) showed that the HBPE was successfully grafted to the GO surface. The mechanical properties and dynamic mechanical analysis (DMA) of the composites demonstrated that GOHBPE played a critical role in mechanical reinforcement owing to the layered structure of GO, wrinkled topology, surface roughness and surface area ascending from various oxygen groups of GO itself, and the inarching of HBPE and the reaction among GO, HBPE, and epoxy resin. The transferred GOHBPE/epoxy resin composites showed 69.1% higher impact strength, 129.1% more tensile strength, 45.3% larger modulus, and 70.8% higher strain compared to that of cured neat epoxy resin. The glass transition temperature (Tg) of GOHBPE/epoxy resin composites was increased from 135 to 141xa0°C and their damping capacity was also improved from 0.71 to 0.91. This study provides guidelines for the fabrication of strengthened polymer composites using phase transfer approach.n Graphical abstractᅟ

Excellent corrosion protection performance of epoxy composite coatings filled with silane functionalized silicon nitride

Silicon nitride was firstly used as anticorrosive pigment in organic coatings. An effective strategy by combining inorganic fillers and organosilanes was used to enhance the dispersibility of silicon nitride in epoxy resin. The formed nanocomposites were applied to protect Q235 carbon steel from corrosion. The anticorrosive performance of modified silicon nitride with silane (KH-570) was investigated by electrochemical impedance spectroscopy (EIS), water absorption and pull-off adhesion methods. With the increase of immersion time, the corrosion resistance as well as adhesion strength of epoxy resin coating and unmodified silicon nitride coating decreased significantly. However, for the modified silicon nitride coating, the corrosion resistance and adhesion strength still maintained 5.7×1010 Ω cm2 and 7.6xa0MPa after 2400-h and 1200-h immersion, respectively. The excellent corrosion resistance performance could be attributed to the chemical interactions between KH-570 functional groups and silicon nitride powders, which mainly came from the easy formation of Si-O-Si bonds. Furthermore, the modified silicon nitride coating formed a strong barrier to corrosive electrolyte due to the hydrophobic of modified silicon nitride powder and increased bonds.

Amorphization of FeNb by mechanical alloying

Abstract Elemental powder mixtures of Fe 1 Nb 1− x were mechanically alloyed in a planetary ball mill. Powders milled for different times were characterized by X-ray diffraction, transmission and scanning electron microscopy, differential thermal analysis and microhardness measurement. The results show that powders with 0.30 ⪕ x ⩽ 0.70 could be amorphized after 30 h milling: the maximum hardness (Hv) of milled Fe 510 Nb 513 powders attained was 1490. Based on a thermodynamical analysis, the glass forming range of the Fe Nb system was calculated, and found to agree with the experimental result very well.

Bio-gel derived nickel/carbon nanocomposites with enhanced microwave absorption

A bio-gel derived strategy was used to construct Ni/C nanocomposites consisting of three-dimensional (3-D) carbon networks with embedded nickel nanoparticles. The amorphous carbon prevents agglomeration of the nickel nanoparticles and thus contributes to a good impedance match. The microwave absorption properties of the Ni/C nanocomposites were optimized according to percolation theory for good impedance matching. As a result, microwave absorbing coatings, which have the advantages of thin thickness (1.75 and 1.5 mm) and light weight (25 and 30 wt%), were achieved with excellent absorbing properties (90% microwave absorption) and a broad bandwidth (13.6–18 GHz and 13.2–18 GHz). The absorbing properties were mainly attributed to the dielectric relaxation processes at 2–18 GHz from the multilevel interface, porous carbon materials and nanoscale nickel nanoparticles in the Ni/C nanocomposites. It is believed that this work not only helps to elucidate the mechanism of absorption but also provides a new design paradigm for determining the optimal content of absorbers using percolation theory. The bio-gel derived strategy paves a possible way for the mass synthesis of microwave absorbers.

Introducing advanced composites and hybrid materials

It is our great pleasure to introduce the inaugural issue of Advanced Composites and Hybrid Materials, a new interdisciplinary journal published by Springer Nature. Advanced Composites and Hybrid Materials provides a dedicated publishing platform for academic and industry researchers and offers the composites and hybrid materials field an opportunity to publish their creative research to exchange newly generated knowledge. With the rapid advancement of materials science and engineering in twenty-first century, especially the development of nanoscience and nanotechnology, the new discoveries from diverse disciplines merge into a central hub of composites and hybrid materials. Composites are defined as materials with two or more constituents with significantly different physical or chemical properties (Fig. 1a). Composites cover a wider range of dimensions of mixing components, while hybrid usually refers to the constituents at the nanometer or molecular level. The revolution of new technologies in composites has generated great impact in every single corner of our daily life [1, 2]. Based on the matrix material, composites can be categorized into polymer composites, ceramic composites, carbon composites, and metal composites. One example of the composite from each category is provided: polymer composites in Fig. 1b [3, 4], ceramic composites in Fig. 1c [5], metal composites in Fig. 1d [6], and carbon composites in Fig. 1e [7]. Nanocomposites, with one dimension of any constituent less than 100 nm, experienced a fast development over the past two decades. The large specific surface area and unique physicochemical properties of nanofillers allow flexible design of nanocomposites with unprecedented functionalities. It is expected that research in nanocomposites will keep its energetic momentum in the next few decades since there are still a lot of challenges that need to be addressed with combined research efforts [8–12]. The integration of different constituents into one unit does not simply generate a mixed property, but also creates some new physicochemical properties that were not present in the individual components. For example, negative permittivity has been discovered in engineered polymer and carbon nanocomposites [13–15], which is not existed in traditional materials.

Superhydrophobic hBN-Regulated Sponges with Excellent Absorbency Fabricated Using a Green and Facile Method

The world faces severe environmental, human and ecological problems when major oil spills and organic discharges are released into the environment. And so it is imperative to develop tools and high performance innovative materials that can efficiently absorb these organic discharges. Furthermore, green, facile methods to produce these advanced materials are also needed. In this paper, we demonstrate a novel porous supersponge based on melamine coated with hBN. This superhydrophobic sponge (with a contact angle >150°) exhibits excellent absorption performance for oils and organic solvents, including good selectivity, high capacity (up to 175u2009g·g−1) and extraordinary recyclability (less than 20% decline after 30 cycles of absorption/squeezing). The synthetic procedure required only ultrasonication and immersion of the sponge in aqueous hBN solution, being a green, cost-effective and scalable production methodology. By virtue of the straightforward and cost-effective fabrication method, along with the excellent absorption performance, hBN-decorated sponges have great promise for real world practical application in the field of oil spills and organic leakage cleanup.

Continuously fabricated transparent conductive polycarbonate/carbon nanotube nanocomposite films for switchable thermochromic applications

Flexible transparent conductive films (TCFs) have attracted more and more attention because of their wide range of potential applications in optical and electronic devices. Industrial-scale manufacturing of high-performance TCFs is a challenge for a wide range of applications. Here, TCFs based on polycarbonate (PC) film successively coated with multi-walled carbon nanotubes (MWNTs) and single-walled carbon nanotubes (SWNTs) are continuously fabricated by a combined spraying and roll-to-roll (R2R) technique. Moreover, such a continuous and scalable method is programmable and fully automated. The synergism between the successively sprayed MWNTs and SWNTs significantly enhances the conductivity and electrical homogeneity of the TCFs. Furthermore, such a film (i.e., PM1S1) still retains its high transmittance (82% at 550 nm), which is only decreased by 6% compared with the PC film. More importantly, no obvious decrease in the conductivity of the TCFs was detected after 1000 cycles of repeated bending, indicating their excellent mechanical flexibility. In addition, due to the synergistic effect, the adhesion and good environmental resistance have been significantly improved. With these advantages, the as-fabricated TCFs show great potential for application in flexible smart windows with switchable thermochromic properties. The proposed technique in this study is an effective approach for fabricating large-scale carbon nanotube/polymer based TCFs, which are promising for a wide variety of practical applications.

The Influence of Hydroxylated Carbon Nanotubes on Epoxy Resin Composites

Hydroxylated multiwall carbon nanotubes (MWNTs)/epoxy resin nanocomposites were prepared with ultrasonic dispersion and casting molding. The effect of hydroxylated MWNTs content on reactive activity of composites is discussed. Then the flexural and electrical properties were studied. Transmission electron microscope was employed to characterize the microstructure of nanocomposites. As a result, the reactive activity of nanocomposites obtained increases with the increasing content of MWNTs. When MWNTs content of the composites is 1u2009wt%, as compared to neat resin, the flexural strength increases from 143u2009Mpa to 156u2009MPa, the modulus increases from 3563u2009Mpa to 3691u2009MPa, and the volume and surface resistance of nanocomposites decrease by two orders of magnitude, respectively.

Hydroxyapatite (HA) Modified Nanocoating Enhancement on AZ31 Mg Alloy by Combined Surface Mechanical Attrition Treatment and Electrochemical Deposition Approach

Hydroxyapatite (HA) nanocoating was electrodeposited on the surface mechanical attrition treated (SMATed) AZ31 magnesium alloy. Phases, morphologies and the adhesion of coating were characterized by X-ray diffraction, scanning electron microscopy (SEM) and 3D optical profiler. The corrosion resistance of the HA coating was tested by potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). The results showed that the HA coating on SMATed sample had a better crystallization than that on original one. The thickness of HA coating increased from 25 to 40 μm. The bonding strength between HA coating and SMATed substrate was higher than that between the coating and untreated counterpart. Potentiodynamic polarization and EIS demonstrated that the corrosion current density of HA coating on SMATed substrate decreased by 30.84% than that on original. The corrosion potential shifted 80.3 mV to the positive direction. The corrosion resistance of coatings on SMATed sample was significantly enhanced. The immersion experiments showed that the HA coatings on SMATed sample exhibited a better biological activity.

In-situ grown nickel selenide onto graphene nanohybrid electrodes for high energy density asymmetric supercapacitors

Nickel selenide (NiSe) nanoparticles uniformly supported on graphene nanosheets (G) to form NiSe-G nanohybrids were prepared by an in situ hydrothermal process. The uniform distribution of NiSe on graphene bestowed the NiSe-G nanohybrid with faster charge transport and diffusion along with abundant accessible electrochemical active sites. The synergistic effect between NiSe nanoparticles and graphene nanosheets for supercapacitor applications was systematically investigated for the first time. The freestanding NiSe-G nanohybrid electrode exhibited better electrochemical performance with a high specific capacitance of 1280 F g-1 at a current density of 1 A g-1 and a capacitance retention of 98% after 2500 cycles relative to that of NiSe nanoparticles. Furthermore, an asymmetric supercapacitor device assembled using the NiSe-G nanohybrid as the positive electrode, activated carbon as the negative electrode and an electrospun PVdF membrane containing 6 M KOH as both the separator and the electrolyte delivered a high energy density of 50.1 W h kg-1 and a power density of 816 W kg-1 at an extended operating voltage of 1.6 V. Thus, the NiSe-G nanohybrid can be used as a potential electrode material for high-performance supercapacitors.