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Objective. To see if 18F-fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT) imaging paired with MR diffusion imaging can help doctors diagnose bone metastases. Methods. From September 2020 to December 2021, a total of 30 individuals with probable bone metastases were recruited for the trial. With an average interval of four days, MAGNETIC resonance whole-body diffusion imaging (MR whole-body diffusion imaging) was performed on each of the 30 patients who had 18F-FDG PET/CT. The SUVmax values of the group with bone metastases were compared to those of the group without bone metastases. In this study, 18F-FDG PET/CT imaging, MR whole-body diffusion imaging, and their combination were examined. The researchers compared the results when 18F-FDG PET/CT imaging, whole-body MRI diffusion scans, and their combination indicated abnormal bone lesions. By comparing the diagnostic efficacy of 18F-FDG PET/CT imaging, MR whole-body diffusion imaging, and their combination, as well as accuracy, sensitivity, and specificity, the three techniques for diagnosing bone metastases will be evaluated for diagnostic usefulness. Results: the SUV max values of patients with bone metastases were significantly different from those of patients without bone metastases, as determined by 18F-FDG PET/CT imaging ( P

At present, new electrode materials still need to be developed to enhance the energy density, cyclability, initial coulombic efficiency and rate capability of lithium-ion batteries (LIBs). Here, we report a simple, rapid, cost-effective and novel technology to prepare MnO2 through the decomposition of KMnO4 under different pH values without surfactants or high temperatures. Moreover, the formation mechanisms of curly MnO2 nanosheets, flower-like MnO2 and onion-like MnO2 are analyzed in depth. The great variation in the electrochemical performance of MnO2 prepared under different pH values clearly indicates the importance of the nanostructure. Furthermore, curly MnO2 nanoflakes fabricated at pH 2 (pH2-MnO2) show good initial coulombic efficiency (ca. 80%) and long cyclability (ca. 1038 mAh g−1 over 150 cycles), which is attributed to their relatively large surface area and stable structure.

Graphene nanosheets prepared by liquid-phase exfoliation tend to aggregate easily and irreversibly in most solvents due to van der Waals forces and high surface energy. This article presents a facile, low-cost and novel approach for the preservation and separation of graphene dispersions by adjusting the temperature and solvent. Using IPA-water mixtures can realize green production of graphene nanosheets, and different physicochemical parameters are achievable by changing the proportion of components. Two valid methods for improving stability were discussed in depth: low-temperature storage as a liquid and as a solid. When graphene dispersions are stored in a liquid phase, agglomeration of nanosheets in mixed solvents can be effectively retarded by strong viscous resistance induced by low temperatures. Frozen powder prepared by liquid nitrogen maintains the nanosheets in a dispersed state and is suitable for long-term preservation in the solid phase in ordinary freezers. Furthermore, rapid separation of graphene nanosheets is a challenging problem that retards industrial production. Flocculation induced by slow freezing can accelerate solid–liquid separation, offering a novel approach to obtain easily dispersed powders. Various patterns could be printed on paper and poly(ethylene terephthalate) by a simple and low-cost screen printing technique using the graphene powder, providing a new platform for scalable, low-cost printing of electronics. Consequently, this scalable and simple strategy can be satisfactorily applied to the preservation and separation of graphene and is expected to extend to other nanomaterials, including MoS2 and h-BN.

To bring graphene closer to its real-world applications, finding a green, low-cost, environment-friendly and less toxic solvent for production of high-quality graphene is highly demanded. However, water, the most widely used green solvent, is generally considered to be a poor solvent for hydrophobic graphene. In this study, we exfoliate graphene nanosheets directly in basic water without surfactants, polymers or organic solvents. The addition of a small amount of ammonia solution achieves the exfoliation of few-layer graphene nanosheets from pristine graphite. Diverse characterization methods are employed to investigate the morphology and quality of as-prepared graphene sheets. The release of gaseous ammonia plays the key role in exfoliation of graphene. The concentration of stable graphene dispersions can reach 0.058 mg/mL.

Liquid exfoliation route has allowed the environmentally friendly, scalable and cost-effective production of high-quality 2D MoS2 nanosheets. However, high capacity achieved by the liquid-exfoliated pristine MoS2 is rarely reported in lithium-ion batteries. In this wok, it is for the first time demonstrated that liquid-exfoliated small-sized MoS2 nanosheets exhibited a high reversible capacity of 1133 mAh g-1 after 130 cycles and an excellent rate capability, which are comparable to the high performances achieved by the available chemical routes

Identifying and eliminating the negative effects of lunar dust are of great importance for future lunar exploration. Since the available lunar samples are limited, developing terrestrial lunar dust simulant becomes critical for the study of lunar dust problem. In this work, beyond the three existing lunar dust simulants: JSC-1Avf, NU-LHT-1D, and CLDS-i, we developed a new high-fidelity lunar dust simulant named as BHLD20. And we concluded a methodology that soil and dust simulants can be produced by variations in portions of the overall procedure, whereby the properties of the products can be controlled by adjusting the feedstock preparation and heating process. The key ingredients of our innovative preparation route include: (1) plagioclase, used as a major material in preparing all kinds of lunar dust simulants; (2) a muffle furnace, applied to expediently enrich the glass phase in feedstock, with the production of some composite particles; (3) a one-step sand-milling technique, employed for mass pulverization without wasting feedstock; and (4) a particle dispersant, utilized to prevent the agglomeration in lunar dust simulant and retain the real particle size. Research activities in the development of BHLD20 can help solve the lunar dust problem.

Improving the rate capability and cycle stability of two-dimensional molybdenum disulfide (MoS2) still holds the key to its application in lithium-ion batteries (LIBs). Here we reported liquid-exfoliated MoS2 nanosheets/graphene composites (MoS2/Gra) towards the high capacity and excellent cycle stability for LIBs. The composites were assembled by pristine graphene and MoS2 nanosheets, which were prepared via the sonication-assisted liquid exfoliation of pristine graphite and MoS2 powders in aqueous surfactant solutions. The composites exhibited the reversible capacity as high as 1145 mAh g−1 after 175 cycles at 100 mA g−1 and excellent rate capability by retaining ∼88% of the capacity at 2000 mA g−1. It is the first time that liquid-exfoliated MoS2/Gra composites show so excellent electrochemical performances and thus are fascinating for LIBs due to the facile, cost-effective and scalable liquid exfoliation route.

In this study, the directly exfoliated graphene prepared by a jet cavitation method was tested as additive in pure water toward tribological applications. Reductions of friction coefficient and wear volume up to 22.8% and 44.4% respectively were achieved by addition of the graphene flakes. The as-prepared aqueous graphene dispersions exhibited high stability against sedimentation, and concurrently maintained their tribological properties after deposited for 15 days. The improvement in lubricating and anti-wear performances can be attributed to the graphene network formed on the sliding surfaces during the test.

The cost-effective, scalable, and reproducible production of a graphene/Si (Gra/Si) composite still holds the key to their commercialization as anodes for lithium-ion batteries (LIBs). Herein, we report the one-step in situ preparation of liquid-exfoliated Gra/Si composites towards practical anodes for commercial LIBs. The Gra/Si composites are prepared by exposing the mixture of pristine graphite flakes and Si nanoparticles to ultrasonication in water/surfactant solutions. The composite's major ingredients are found to be highly exfoliated graphene and crystal Si nanoparticles. As the anode in LIBs, the composite with ∼47.3 wt% Si shows improved electrochemical performance, with superiorly rate performance and a high reversible capacity of 700 mA h g−1 after 100 cycles. The improved performance is ascribed to the graphene-derived 3D porous structure, which makes the Si nanoparticles well dispersed and buffers the volume change during the charge–discharge cycles. With respect to the simple and scalable liquid-exfoliated Gra/Si composite, the achieved performance here is fascinating for commercial LIBs.

In this study, the tribological behavior of in-situ exfoliated graphene for water-based lubricants is investigated. The aqueous graphene dispersions show high stability due to the assistance of a non-ionic surfactant, Triton X-100. The steel–steel ball-plate tribotest results reveal that the in-situ exfoliated graphene possesses brilliant frictional and anti-wear properties. Compared with pure deionized water, the graphene-enhanced lubricants can offer 81.3% and 61.8% reduction in friction coefficient and wear scar diameter (i.e. a reduction in wear volume by two orders of magnitude), respectively, owing to the formation of a protective graphene layer at the sliding contact zone. The performance of in-situ exfoliated graphene is also better than that of graphene oxide at the same additive concentration. Furthermore, the as-prepared lubricants exhibit enhanced lubrication effect even in high load and diverse velocity cases. It is proposed that the surfactant, Triton X-100, eases the deposition procedure of the graphene layer by adjusting the dispersion wettability of the sliding surfaces, thus leading to the superior tribological properties.

Though the graphene-based films prepared by vacuum filtration of graphene dispersions can be well and easily prepared so far and show great prospects in conductive, transparent, and flexible devices and coatings, the nature of these films has been rarely investigated. In order to reveal how graphene flakes constitute these films, herein we prepared a thin graphene-based film by vacuum filtering graphene dispersions and characterized the film by diverse techniques. Microscopic analyses evidenced the layer structure nature of the film. Raman spectra, transmission electron microscopy, and X-ray diffraction results indicate that the film is neither graphene nor graphite, but intrinsically a graphene block constituted by numerous graphene flakes which are randomly stacked. Though aggregation of graphene flakes happens in the filtration process, the aggregation is not a process to drive graphene flakes stacked in Bernal AB style to form bulk graphite. The adjoining graphene flakes are poorly coupled, likely due to the interlayer adventitious impurities introduced from liquid-phase processing.

The comprehensive effects of the dimensions and the thickness of boron nitride nanosheets (BNNSs) on the composite properties are evaluated in this study. BNNSs were directly prepared in cellulose acetate (CA)–acetone solution and separated into different size ranges by multi-step centrifugation, while composite films were then fabricated by employing as-prepared nanosheets as fillers and CA, a biodegradable polymer, as the matrix. Break elongation was significantly increased by filling large BNNSs due to the reduction of bubble defects and the slowdown of the crack propagation. Importantly, the “zipper crack” consists of two ordered and meshing protruding teeth, contributing to high energy absorption and fracture toughness. A large surface area in one plane and high stability of the BNNSs can effectively protect the polymer matrix from atomic oxygen (AO) erosion. Furthermore, the embedment of BNNSs with high aspect ratio can achieve significant enhancement of mechanical properties and AO erosion resistance. All results indicate that the boron nitride sheet is a promising nanofiller for polymeric composites and, more importantly, high aspect ratio is the critical factor for achieving the desired improvement.

We demonstrate that in water–surfactant solutions, adding ethanol can lead to graphene dispersions of high concentration (∼0.46 mg mL−1). For both ionic and non-ionic surfactants, ∼10 wt% addition of ethanol is found to enhance the exfoliation efficiency and thus the graphene concentration up to three times. This enhancement is attributed to the combination of decreasing mixing enthalpy by ethanol addition and enhancing stability of surfactants. This method opens a whole new vista for preparing high-concentration graphene dispersions.

Based on a hydrodynamic mechanism, a novel, scalable and rapid production of relatively defect-free graphene nanosheets (GNSs) by a high shear mixer is proposed in this paper. The synergistic enhancement of shear forces and collision effects can result in an effective exfoliation of ultrathin GNSs. Moreover, the productivity and dimension distribution of GNSs can be easily controlled by adjusting hydrodynamic forces. Utilizing the small stator, the concentration of mono- and multi-layer GNSs prepared for 1 h in 40 vol% IPA–water mixtures can reach 0.27 mg ml−1. Almost all GNSs are less than 1 μm in average size and 2 nm in thickness. Furthermore, the mixtures of isopropanol (IPA) and water are low boiling, green, inexpensive, and have excellent solubility for GNSs. The optimal volume fraction of IPA–water mixtures for preparing GNSs is co-determined by the Hansen solubility parameter distance (Ra), surface tension and viscosity. More importantly, graphite particles have strong physical interactions with hydrodynamic forces, but GNSs structure also can remain relatively defect-free. Consequently, this scalable, rapid and high-yield method can be satisfactorily applied in the production of GNSs and other two-dimensional (2D) materials.

Nonmetal materials of waste printed circuit boards (PCBs) contain 50–70 wt% fiberglasses, which are usually abandoned as waste-byproducts during the recycling of waste PCBs. In this paper, we demonstrated a novel reuse of the fiberglasses recovered from waste PCBs for noise reduction application. The sound absorption performance of the recovered fiberglasses (RFG) was investigated by considering the effect of material thickness and bulk density. Also, the influence of covering layers on the absorption ability was studied. Results show that the high porous structure of the RFG leads to an excellent sound absorption ability in a broad-band frequency range. Average sound absorption coefficient of over 0.8 can be achieved in 100–6,400 Hz for 30 mm RFG sample. It is found that when the sample thickness increases the low-frequency absorption of RFG is significantly improved. All the results indicate that the reuse of RFG for noise reduction represents a promising way to realize high value-added utilization of waste PCBs.

In this study, we have demonstrated a strategy by which graphene was used to reduce the bubble defects and enhance the mechanical properties in graphene/cellulose acetate (Gr/CA) composite films. Mono- and multilayer graphene flakes were successfully prepared in the water–acetone mixtures by a jet cavitation method. Moreover, outstanding enhancement of mechanical properties of Gr/CA composite films were obtained at relatively low concentration of graphene flakes. Young’s modulus of these composite films increased linearly with the graphene flakes loading, due to the significantly high surface area of graphene and strong interactions between graphene flake and CA. Furthermore, three-dimensional channel formed by graphene flakes could increase the degassing speed and reduce the negative effects of bubbles. The Gr/CA composite has excellent mechanical properties and, more importantly, it is a natural and environmentally friendly polymer composite.

The aim of this study is to investigate the feasibility of using glass fibers, a recycled material from waste printed circuit boards (WPCB), as sound absorption and thermal insulation material. Glass fibers were obtained through a fluidized-bed recycling process. Acoustic properties of the recovered glass fibers (RGF) were measured and compared with some commercial sound absorbing materials, such as expanded perlite (EP), expanded vermiculite (EV), and commercial glass fiber. Results show that RGF have good sound absorption ability over the whole tested frequency range (100-6400 Hz). The average sound absorption coefficient of RGF is 0.86, which is prior to those of EP (0.81) and EV (0.73). Noise reduction coefficient analysis indicates that the absorption ability of RGF can meet the requirement of II rating for sound absorbing material according to national standard. The thermal insulation results show that RGF has a fair low thermal conductivity (0.046 W/m K), which is comparable to those of some insulation materials (i.e., EV, EP, and rock wool). Besides, an empirical dependence of thermal conductivity on material temperature was determined for RGF. All the results showed that the reuse of RGF for sound and thermal insulation material provided a promising way for recycling WPCB and obtaining high beneficial products.

Atomic oxygen (AO) is a dominant component of the low earth orbit and can erode most spacecraft material. We demonstrated the application of graphene to enhance AO erosion resistance of spacecraft polymers. Graphene-reinforced epoxy resin nanocomposites were prepared by solidification of epoxy resin in solution with dispersed graphene flakes and their AO erosion resistance was investigated in a plasma-type ground-based AO effects simulation facility. The nanocomposites were characterized by X-ray diffraction, scanning electron microscopy, thermogravimetric analysis, and X-ray photoelectron spectroscopy. Results based on erosion kinetics revealed that a 46 % decrease in mass loss and a 47 % decrease in erosion yield were achieved by addition of only 0.5 wt% of graphene. Further analysis of the surface morphology and composition showed that the graphene nanoflakes could serve as barriers to protect underneath from AO erosion. Thus, this approach provides a novel route for improving durability and reliability of spacecraft material, especially polymers.

Superfine spherical fire-extinguishing powder, ammonium dihydrogen phosphate (ADP, NH4H2PO4), was prepared by spray drying and modified in situ with methyl hydrogen silicone oil (MHSO) emulsion and the fluorinated surfactant FK-510. The influences of the MHSO mass ratio on the hydrophobicity, surface composition, surface morphology, dispersion and particle-size distribution of the NH4H2PO4 were studied, and the influence of the drying air temperature on the decomposition of the NH4H2PO4 was also researched. The results indicate that the MHSO and FK-510 congregate on the particle surfaces and then form a hydrophobic shell. This shell improves the particle hydrophobicity and leads to a fine dispersion of the particles. During the process of preparing the precursor solution, 3 wt% (based on the weight of NH4H2PO4) was chosen as the optimum value of the MHSO mass ratio. During the spray drying, a low absolute humidity of the air should be maintained, and it is very important to keep the exit-air temperature below 100 °C to avoid decomposition.

Sonication-assisted liquid-phase exfoliation of graphite makes facile, scalable, and low-cost graphene production possible, but there is little information about how sonication-related factors such as vessel diameter (D) and liquid height (H) affect this process and how to scale-up this technique. In this article, the dependence of the sonication-assisted few-layer graphene (FLG) production on D and H was investigated based on experiments and numerical simulation which was performed by finite element method to determine cavitation-related parameters. It was found that by essentially changing the cavitation phenomenon, D and H could critically affect the FLG concentration, FLG yield, injected power, and production efficiency. Combined experimental and simulational analyses reveal that though D and H can change both cavitation volume and cavitation volume fraction, it is the cavitation volume fraction that directly relates to the FLG concentration and production efficiency with a monotonically increasing trend, while the FLG yield and injected power are almost proportional to the cavitation volume, which in turn follows a linear increasing trend with the sample volume. The practical importance for industrial FLG production may lie in the following: (1) D and H should be carefully designed to obtain high cavitation volume fraction to gain high production efficiency and FLG concentration or output-input ratio and (2) large D, H, or sample volume is necessary for achieving large cavitation volume to enhance the FLG yield. Moreover, enhancement in pressure amplitude or cavitation intensity could also favor FLG production. These results have verified the importance of D and H which are often ignored when studying graphene production, and will provide important information on designing large-sized vessels for mass-producing graphene by sonication.

In this study, a jet cavitation device aimed at producing two-dimensional nanosheets was designed. The effects of cavitation generator type and jet pressure on the cavitation inception and intensity were examined by monitoring the changes of sound pressure level (ΔSPL). As such, the optimized cavitation generator with the best cavitation capability under the same ambient condition was determined. Further, BN and MoS2, two kinds of layered materials, were exfoliated into individual flakes in aqueous solutions by this jet cavitation device. By investigating the morphology of these exfoliated flakes via scanning electron microscopy and transmission electron microscope, it was found that these pristine materials were mostly exfoliated into two-dimensional nanosheets, among which even monolayers were generally presented. This exfoliation process happened mainly due to the cavitation-induced intensive tensile stress acting on the layered materials. As graphene has been produced by this device successfully, it is anticipated that this jet cavitation device is suitable for producing other various two-dimensional nanosheets.

Surface modification of carborundum (SiC) particles with a modifying agent, with simultaneous ultrafine comminution in an air jet mill, was studied in this work. The production rate of SiC and the viscosity of the SiC-paraffin oil suspension were used to evaluate the performance of comminution and modification. The experimental results indicated that the modifying agent bonded onto the surface of the SiC to form an organic layer in the integrated process of modification and comminution. The types and content of modifying agents and the temperature of the compressed air have a great effect on the performance of ultrafine modified SiC, and there are some contradictory aspects between modification and comminution in the integrated process. According to the targets of both surface modification and ultrafine comminution, the optimum temperature of compressed air and feed rate of the modifying agent solution was 60 °C and 2 ml/min respectively, when the modifying agent A-151 was adopted to obtain the modified ultrafine SiC in one step.

The feasibility of reusing the recycled glass fibers (RGF) from nonmetals of waste printed circuit boards in polypropylene (PP) composites is studied by mechanical properties, vicat softening temperature and heat distortion temperature. The influence of RGF on reinforcing mechanism of the composites is watched under scanning electron microscopy (SEM) in situ tensile test. The results show that the mechanical and thermal properties of the RGF/PP composites can be significantly improved by adding the RGF into PP. In situ SEM observation results show that the RGF are the excellent supporting bodies and can effectively lead to mass microcracks. Crack initiation, propagation, and fiber breakage dissipate tremendous energy. Therefore, the mechanical properties are reinforced. All the above results indicate that the reuse of RGF in the PP composites represents a promising way for closing the recycling loop and realizing the high added value utilization. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010

A great amount of work has been done over the past few years to reuse the nonmetals recycled from waste printed circuit boards in polypropylene (PP) composites. This is because of the very fast generation rate of nonmetal pollution in the world each year and the very fast growing rate of PP applications in industries. This work focuses on the dynamic effects of nonmetals of different particle sizes on the tensile properties and reinforcing mechanisms of nonmetal/PP composites by in situ scanning electron microscopy tensile testing. The observed results show that the dominant deformation mechanism in pure PP is shear yielding. When fine nonmetals are filled into PP, mass microcracks are initiated. The glass fibers first resist the cracks and undertake the loading when they propagate. The crazes propagate slowly and then break the glass fibers. When coarse nonmetals are filled into PP, interfacial debonding and mass microcracks are initiated. A crack is either terminated when it meets another fiber–particulate bundle or branched into finer mass crazing. Interfacial debonding, crack initiation and propagation, and fiber pullout and breakage dissipate tremendous energy. These factors cause improvements in the strength and rigidity of nonmetal/PP composites. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009

The printed circuit boards (PCBs) contain nearly 70% nonmetal materials, which usually are abandoned as an industrial solid-waste byproduct during the recycling of waste PCBs. However those materials have abundant high-value glass fibers. In this study, a novel fluidized bed process technology for recycling glass fibers from nonmetal materials of waste PCBs is studied. The recycled glass fibers (RGF) are analyzed by determination of their purity, morphology and surface chemical composition. This process technology is shown to be effective and robust in treating with nonmetal materials of waste PCBs. The thermoset resins in the nonmetal materials are decomposed in the temperature range from 400 degrees C to 600 degrees C. And the glass fibers are collected at high purity and recovery rate by the cyclone separators without violating the environmental regulation. This novel fluidized bed technology for recycling high-value glass fibers from nonmetal materials of waste PCBs represents a promising way for recycling resources and resolving the environmental pollutions during recycling of waste PCBs.

Flexural strength and flexural modulus of the composites can be successfully improved by filling nonmetals recycled from waste printed circuit boards (PCBs) into polypropylene (PP). By using scanning electron microscopy (SEM), the influence of nonmetals on fracture behavior of PP composites is investigated by in situ flexural test. Observation results show that the particles can effectively lead to mass micro cracks instead of the breaking crack. The process of the crack initiation, propagation and fiber breakage dissipate a great amount of energy. As a result, the flexural properties of the composites can be reinforced significantly. Results of the in situ SEM observation and analysis to the dynamic flexural process supply effective test evidence for the reinforcing mechanism of the nonmetals/PP composites on the basis of the energy dissipation theory.

Superfine spherical hollow ammonium dihydrogen phosphate (NH4H2PO4) fire-extinguishing particles are first produced by the spray-drying method. The particles prepared at drying gas inlet temperature ranging from 180°C to 220°C are composed of NH4H2PO4. When the proportion of FK-510 increases from 5 wt%to 10 wt%, the surfaces of the as-prepared particles become rougher, and the volume mean size of particles increases from 11.25 to 15.44 µm. When the proportion of FK-510 increases from 10 to 15 wt%, the amount of broken spherical hollow particles clearly decreases and the volume mean size of particles decreases from 15.44 to 13.5 µm. The flow rate and bulk density of the particles prepared from the solution containing the proportion of FK-510 ranging from 5 to 15 wt% decreases with an increase in the proportion of FK-510. When 15 wt% of FK-510 is added, diesel oil contact angle of particles markedly increases. In addition, water contact angle of particles decreases with an increase in the proportion of FK-5...

Superfine spherical hollow ammonium dihydrogen phosphate fire-extinguishing particles are prepared by spray drying and modified in situ with silicon oil emulsion. The results show that the amount of rough particles increased observably when the proportion of silicon oil emulsion is increased from 9 to 15 wt%, while no significant difference is detected when the proportion of silicon oil emulsion was varied from 0 to 9 wt%. The flowability of particles is improved with an increase in the proportion of silicon oil emulsion; 9.0 wt% is the optimal proportion of silicon oil emulsion for improving the hydrophobic performance of particles. Fire-extinguishing tests show that the fire-extinguishing capability of spray-dried superfine spherical hollow ammonium dihydrogen phosphate fire-extinguishing particles is much better than the two varieties of existing superfine dry chemical fire-extinguishing agents.

Toughness, strength, and rigidity of the composites can be improved simultaneously by filling plerosphere particles into polypropylene (PP). The mechanism of improving the mechanical properties of the composites is studied on the basis of the energy dissipation theory. By using scanning electron microscopy (SEM), the crack initiation, propagation, and termination on the plerosphere/PP composites are investigated by in situ tensile test. Observation results show that the particles can effectively lead to a number of microcracks instead of the breaking crack. These microcracks formation consumes tremendous energy. As a result, the toughness and strength of the polymer can be improved. Results of the in situ SEM observation and analysis to the dynamic process supply effective test evidence for the toughening mechanism of the plerosphere/PP composite on the basis of the energy dissipation theory. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007

A novel technology for powder dispersion and surface modification was studied by experiment in this paper. In the process, powders are dispersed by the nozzle and the atomized modifying agent is sprayed into the dispersed particles and coated on the surface at the same time. Silica, mica and talc powders were dispersed and modified by this technology, the performance of powder dispersion is evaluated by the scanning electron microscope (SEM), and the performance of surface modification is evaluated in advance by the viscosity of powder-paraffin suspension. In experiment, the modified silica was filled in the polypropylene (PP), the impact fractographs, notched impact and tensile properties of the PP composites were studied, the results indicate that the developed technology is effective for powders dispersion and surface modification.

The growth behavior and surface topography of the deposited films formed from silane coupling agents on silicon dioxide substrate (0001) via vapor phase deposition was investigated using atomic force microscopy (AFM). The surface topography of the films adsorbed on the silicon dioxide substrates is dissimilar with different silane coupling agents and different deposition conditions: (1) the films adsorbed on the silicon dioxide substrate become smoother with the increasing temperature of the silicon dioxide substrate; (2) the surface roughness of the films increases with the increasing concentration of the silane coupling agent solutions; (3) with the increasing temperature of the carrier gas, the surface roughness of the films decreases firstly and then increases; (4) with the increasing time of deposition, the surface roughness of the films increases firstly, then decreases and subsequently increases again. In experiments, the films adsorbed on the silicon dioxide substrate was rinsed ultrasonically with toluene, the results indicate that the silane coupling agent adsorbed on the substrate by physisorption and chemisorption: the chemisorbed coupling agents present island morphology and the physisorbed coupling agents are deposited on the substrate between the islands to decrease the surface roughness of the film.

The massive production of graphene by jet cavitation method with high productivity is demonstrated. Effects of the critical processing parameters on the product dispersions are studied systematically. Experimental results show that high yield of graphene flakes relies on appropriate initial concentration of graphite, high jet pressure, and long treating time. By processing a large batch (10 L) of graphite dispersion for 8 h under 20 MPa in the jet cavitation device, an exfoliation fraction of up to ~12 wt% was achieved. Based on statistical analysis of atomic force microscopy, the as-produced graphene flakes were proved to be highly exfoliated, while the distributions of flake thickness and area became narrower with the increase of treating time. Raman spectra confirm that few defects on the graphene basal planes were induced. In general, the presented approach shows advantages in comparison with peer liquid phase exfoliation methods and thus provides a new route in efficiently producing high-quality graphene in large scale.

Spacecraft traveling in low earth orbit (LEO) will react with environmental factors, such as atomic oxygen (AO), ultraviolet radiation (UV) and vacuum ultraviolet radiation (VUV), which may severely affect the lifetime of the spacecraft. Teflon, including PTFE (polytetrafluoroethylene) Teflon and FEP Teflon, is a commonly used spacecraft material. Existing studies showed that Teflon could be eroded by AO in LEO but with a lower erosion yield than most of other spacecraft materials. However, its erosion yield increases in long-term flight experiments, which might be caused by synergism of several environmental effects. In this work, experiments were conducted to investigate the erosion effects of atomic oxygen on PTFE Teflon in a ground-based simulation facility. The samples, before and after the experiments, were compared in appearance, mass, surface morphology, optical properties and surface composition. We also analysed the influence of temperature, ultraviolet radiation and vacuum ultraviolet radiation on the atomic oxygen effects. Four conclusions can be drawn: first, PTFE Teflon is eroded severely in the ground-based facility, where the erosion yield is higher than that in the flight experiments and identical to those from other ground-based facilities. Secondly, the erosion yield increases with the sample temperature. Thirdly, ultraviolet radiation has little effect on the mass loss and erosion yield of the Teflon sample in the AO experiment. Lastly, there may be some synergistic effects of atomic oxygen and vacuum ultraviolet radiation, which could be one of the main factors that cause the more severe erosion of Teflon.

Plerospheres, defined here as superfine spherical particles (0.5–5 μm) separated from fly ash (rather than as other solid spherical particles, as some have used the term), are separated from coal fly ash but are dramatically different from it. Plerospheres can be used as polymer fillers to improve the properties of composites. With plerospheres used as fillers for polypropylene (PP) and unplasticized poly(vinyl chloride) (UPVC), the effects of the filler content, the particle sizes of the plerospheres, and the coupling agent on the composite properties were studied. The particle sizes of the plerospheres were 2 and 5 μm. The results suggested that the notched impact properties both at a normal temperature and a low temperature and the tensile and flexural properties of plerosphere/PP increased significantly when the content was increased from 0 to 30 wt % and further increased with the addition of a coupling agent. Differential scanning calorimetry indicated that the thermal properties of the plerosphere/PP composite improved. The surface characteristics and morphology of the impact fracture surface were examined in detail with scanning electron microscopy. The rheological performance of plerosphere/UPVC pipe composites obviously improved; the plasticizing time was shortened, and the maximum torque was reduced. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 126–131, 2004

This paper reports the use of a colloidal Pd0 catalysis system to metallize the surface of precipitators separated from coal fly-ash, and metals such as Cu, Ni etc. are deposited on the precipitators surface. Alternatively, according to the characteristic surface of cenospheres, an Ag coating catalysis system is adopted to first deposit Ag on the cenospheres surface, followed, if necessary, by the deposition of other metals such as Cu, Ni, etc. on the Ag coating to produce monolayer and multilayer metal-coated cenospheres. The surface characteristics and the morphologies of the metal coatings are examined in detail with scanning electron microscopy (SEM), energy dispersive spectroscopy (EDX) and X-ray photoelectron spectroscopy (XPS) techniques. It can be shown that the quality of metal coatings derived from the Ag coating catalysis system, is better than that of the colloidal Pd0 catalysis system.

This study investigated the feasibility of using acrylonitrile-butadiene-styrene (ABS) waste plastic and nonmetal particles from waste printed circuit boards (WPCB) to manufacture reproduction composites (RC), with the aim of co-recycling these two waste resources. The composites were prepared in a twin-crew extruder and investigated by means of mechanical testing, in situ flexural observation, thermogravimatric analysis, and dimensional stability evaluation. The results showed that the presence of nonmetal particles significantly improved the mechanical properties and the physical performance of the RC. A loading of 30 wt% nonmetal particles could achieve a flexural strength of 72.6 MPa, a flexural modulus of 3.57 GPa, and an impact strength of 15.5 kJ/m2. Moreover, it was found that the application of maleic anhydride-grafted ABS as compatilizer could effectively promote the interfacial adhesion between the ABS plastic and the nonmetal particles. This research provides a novel method to reuse waste ABS and WPCB nonmetals for manufacturing high value-added product, which represents a promising way for waste recycling and resolving the environmental problem.

Nonmetal materials take up about 70 wt% of waste printed wiring boards (WPWB), which are usually recycled as low-value fillers or even directly disposed by landfill dumping and incineration. In this research, a novel reuse ofthe nonmetals to produce porous composites for sound absorbing application was demonstrated. The manufacturing process, absorbing performance and mechanical properties of the composites were studied. The results show that the high porous structure of the composites leads to an excellent sound absorption ability in broad-band frequency range. Average absorption coefficient of above 0.4 can be achievedby the composite in the frequency range from 100 to 6400 Hz. When the particle size is larger than 0.2 mm, the absorption ability of the composite is comparable to that of commercial wood-fibre board and urea-formaldehyde foam. Mechanical analysis indicates that the porous composites possess sufficient structural strength for self-sustaining applications. All the results indicate that producing sound absorbing composite with nonmetal particles from WPWB provides an efficient and profitable way for recycling this waste resource and can resolve both the environment pollution and noise pollution problems.

Kapton, a commonly used spacecraft material, is studied to investigate the atomic oxygen (AO) erosion effects in a plasma-type ground-based AO effects simulation facility. The samples before and after the experiments are compared in aspect, mass and surface morphology. The reaction characteristics of the material in the facility are obtained. The contribution of AO and ionic oxygen to mass loss in the sample and the reaction mechanism between the different particles and samples are analysed. It is concluded that neutral AO is the major cause of material erosion and mass loss and that the collision of energetic ions may accelerate the oxidation reaction.

The reaction of N-n-Bu4MnO4 with Mn(OAc)2·4H2O, pyridine and butyric acid in absolute EtOH leads to the high-yield formation of the oxo-centered trinuclear Mn complex, [Mn3O(O2CC3H7)6(C5H5N)3]·ClO4. The complex crystallizes in orthorhombic, space group Pna21 with a=19.588(7), b=20.194(6), c=12.491(5) A. Variable temperature solid state magnetic susceptibility study shows that the antiferromagnetic exchange interaction is weak, and the exchange integral J=−12.36 cm−1.

The application of graphene (Gr) to enhance atomic oxygen (AO) erosion resistance and mechanical properties was demonstrated in this study. Gr-reinforced cellulose acetate (CA) composite films were obtained by flattening with a glass rod, and the AO erosion resistance was investigated in a plasma-type, ground-based AO effect simulation facility. Significant improvements in the mechanical properties and AO erosion resistance were achieved at relatively low Gr contents. A 596 7% decrease in the mass loss and a 126 3% increase in the tensile strength were achieved by the addition of only 1 wt % Gr. Moreover, the layered structure of the fractured surfaces and the excellent mechanical properties illustrated the homogeneous dispersion of Gr in the CA matrix and the strong interactions between Gr and CA. Furthermore, Gr flakes served as shields to defend the underside of CA from AO erosion because of the specific two-dimensional structure and outstanding AO erosion resistance. Therefore, this research provides a new and effective strategy for improving the mechanical strength and AO erosion resistance of polymer materials. VC 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40292.

Searching for a method for low-cost, easily manageable, and scalable production of boron nitride nanosheets (BNNSs) and exploring their novel applications are highly important. For the first time we demonstrate that a novel and effective hydrodynamics method, which involves multiple exfoliation mechanisms and thus leads to much higher yield and efficiency, can realize large-scale production of BNNSs. The exfoliation mechanisms that multiple fluid dynamics events contribute towards normal and lateral exfoliation processes could be applied to other layered materials. Up to ~95% of the prepared BNNSs are less than 3.5 nm thick with a monolayer fraction of ~37%. Compared to the conventional sonication and ball milling-based methods, the hydrodynamics method has the advantages of possessing multiple efficient ways for exfoliating BN, being low-cost and environmentally-friendly, producing high quality BNNSs in high yield and efficiency, and achieving concentrated BNNSs dispersions even in mediocre solvents. It is also shown for the first time that BNNSs can be utilized as fillers to improve the oxygen-atom erosion resistance of epoxy composites which are widely used for spacecraft in low earth orbit (LEO) where atom oxygen abounds. An addition of only 0.5 wt% BNNSs can result in a 70% decrease in the mass loss of epoxy composites after atom oxygen exposure equivalent to 160 days in an orbit of ~300 km. Overall, the demonstrated hydrodynamics method shows great potential in large-scale production of BNNSs in industry in terms of yield, efficiency, and environmental friendliness; and the innovative application of BNNSs to enhancing oxygen-atom erosion resistance of polymeric composites in space may provide a novel route for designing light spacecraft in LEO.

Though chemical modification of graphene based on Hummers method has been most widely used to tailor its properties and interfacial characteristics, a method which could achieve definitive and controllable groups and properties is still highly required. Here, we demonstrate a high-vacuum oxidation strategy by atomic oxygen (AO) and investigate the AO induced functionalization and wettability transition in films made from basal-defect- and oxide-free graphene dispersions. These graphene-based films are neither graphene nor graphite, but graphene blocks constituted by numerous randomly stacked graphene flakes. It is found that AO induced functionalization of these films through the formation of epoxy groups, sp3 configuration, ether, and double and triple C–O groups. The films turn to be hydrophilic after exposed to AO. The contact angle increases with AO exposure time. This phenomenon is attributed to the lower surface roughness induced by collision and/or edge erosion of energetic ions to the film surface and is further explained by the Wenzel model. The demonstrated strategy can overcome limitations of Hummers method, provide possibility to gain functionalization and wettability transition in liquid-phase exfoliated basal-defect- and oxide-free graphene in the dry environment, and may extend the study and application of this material in spacecraft in low earth orbit.