Increasing Graphene Oxide Content Research Articles

Defining the immunological compatibility of graphene oxide-loaded PLGA scaffolds for biomedical applications

Graphene oxide (GO), a carbon-based nanomaterial, presents significant potential across biomedical fields such as bioimaging, drug delivery, biosensors, and phototherapy. This study examines the effects of integrating GO into poly(lactic-co-glycolic acid) (PLGA) scaffolds on human immune cell function. Our results demonstrate that high concentrations of GO reduce the viability of peripheral blood mononuclear cells (PBMCs) following stimulation with anti-CD3 antibody. This reduction extends to T lymphocyte activation, evident from the diminished proliferative response to T cell receptor engagement and impaired differentiation into T helper subsets and regulatory T cells. Interestingly, although GO induces a minimal response in resting monocytes, but it significantly affects both the viability and the differentiation potential of monocytes induced to mature toward M1 pro-inflammatory and M2-like immunoregulatory macrophages. This study seeks to address a critical gap by investigating the in vitro immunomodulatory effects of PLGA scaffolds incorporating various concentrations of GO on primary immune cells, specifically PBMCs isolated from healthy donors. Our findings emphasize the need to optimize the GO to PLGA ratios and scaffold design to advance PLGA-GO-based biomedical applications. Statement of significanceGraphene oxide (GO) holds immense promise for biomedical applications due to its unique properties. However, concerns regarding its potential to trigger adverse immune responses remain. This study addresses this critical gap by investigating the in vitro immunomodulatory effects of PLGA scaffolds incorporating increasing GO concentrations on human peripheral blood mononuclear cells (PBMCs). By elucidating the impact on cell viability, T cell proliferation and differentiation, and the maturation/polarization of antigen-presenting cells, this work offers valuable insights for designing safe and immunologically compatible GO-based biomaterials for future clinical translation.

Collaborative polarization in a solution of coupled hydroxychloroquine-graphene oxide: Optoelectrical measurements

Optical UV–vis and electrical impedance measurements were conducted at room temperature on aqueous solutions with hydroxychloroquine (HCQ) and graphene oxide (GO) molecules. Remarkably, at sufficiently high GO concentration, the HCQ-GO solution exhibited the least loss factor and the Debye relaxation process, suggesting that the polarization of coupled HCQ-GO molecules is cooperative and, hence, correlated within the Debye relaxation time. Indeed, our systematic molecular dynamic calculations of the equilibrium Dipole Auto-Correlation Function (DACF) showed that adding GO enhances the decay relaxation time of DACF for HCQ samples. Moreover, the depression of the characteristic UV absorption peak (at ∼ 342 nm) with increasing GO concentration validated the presence of the HCQ-GO interaction in our samples, agreeing with our calculation based on the simplified time-dependent density functional theory. Our work is, thus, timely regarding the current high demand for a method to remove HCQ from the aqueous environment. It is also relevant to drug delivery applications considering the anticancer efficacy of HCQ and the biocompatible GO as a potential drug carrier.

Preparation and separation performance of biomimetic polycaprolactone/graphene oxide composite membrane

The treatment of oil and water pollutants generated in industrial production and daily life is an urgent issue that needs to be addressed globally. Inspired by superhydrophobic self-cleaning lotus leaves, durable and sturdy superhydrophobic water-filled barriers, and lightweight bird bones with hollow structures, researchers can obtain superhydrophobic surfaces by creating rough surfaces of layered micro- and nanostructures. In this study, hydrophobic polycaprolactone (PCL) membranes with layered structures were prepared by electrospinning. The surface roughness of the PCL membrane was improved by compounding graphene oxide (GO) functional components on the PCL membrane surface, thereby enhancing its hydrophobicity. The infrared spectrum of the PCL/GO membrane shows that PCL and GO are physically mixed, and no chemical changes occur during the electrospinning process. Scanning electron microscopy (SEM) images of the composite fibre membranes reveal the interconnections between fibres. Fourier transform infrared spectroscopy (FTIR) provides information on the chemical components of the membranes. Thermogravimetric analysis (TGA) was employed to assess the thermal stability of the membranes. The oil-water separation test demonstrated that the PCL/GO membrane exhibited a separation efficiency of 99.94% for hexane-water mixtures. In the oil adsorption test, the maximum adsorption capacity of the membrane for n-hexane was 35.8 g/g. In the contact angle measurement experiment, the water contact angle of the nanofiber membrane increased from 120.12° to 140.15° with increasing GO content, indicating that the composite membrane exhibited enhanced hydrophobicity.

Enhancing Water Resistance and Mechanical Properties of Cemented Soil with Graphene Oxide.

Although cemented soil as a subgrade fill material can meet certain performance requirements, it is susceptible to capillary erosion caused by groundwater. In order to eliminate the hazards caused by capillary water rise and to summarize the relevant laws of water transport properties, graphene oxide (GO) was used to improve cemented soil. This paper conducted capillary water absorption tests, unconfined compressive strength (UCS) tests, softening coefficient tests, and scanning electron microscope (SEM) tests on cemented soil using various contents of GO. The results showed that the capillary water absorption capacity and capillary water absorption rate exhibited a decreasing and then increasing trend with increasing GO content, while the UCS demonstrated an increasing and then decreasing trend. The improvement effect is most obvious when the content is 0.09%. At this content, the capillary absorption and capillary water absorption rate were reduced by 25.8% and 33.9%, respectively, and the UCS at 7d, 14d, and 28d was increased by 70.32%, 57.94%, and 61.97%, respectively. SEM testing results demonstrated that GO reduces the apparent void ratio of cemented soil by stimulating cement hydration and promoting ion exchange, thereby optimizing the microstructure and improving water resistance and mechanical properties. This research serves as a foundation for further investigating water migration and the appropriate treatment of GO-modified cemented soil subgrade.

Morphological, compatibility, rheological and mechanical properties of graphene oxide/PLA/XNBR-g-GMA/XNBR: empirical and theoretical approaches

ABSTRACT The incompatible thermoplastic poly lactic acid/carboxylated acrylonitrile butadiene rubber (PLA/XNBR) was prepared, and the effect of graphene oxide (GO) as a reinforcement and glycidyl methacrylate (GMA)-grafted XNBR (XNBR-g-GMA) as a compatibilizer on the properties of PLA/XNBR blend was investigated in this research. The microstructure, mechanical behavior, thermal, rheology, and dynamic mechanical properties of PLA/XNBR composites were investigated by field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), differential scanning calorimetry (DSC), tensile test, and dynamic mechanical thermal analysis (DMTA). The incorporation of XNBR-g-GMA improved the compatibility of the PLA/XNBR blend phases, as confirmed by microstructure and DMTA analysis. The results of the mechanical properties showed that with an increase in GO content in the PLA/XNBR/XNBR-g-GMA matrix, there was a significant improvement in tensile strength, Young’s modulus, hardness, and impact strength. In order to validate the experimental mechanical and rheological results, various theoretical models were applied and a good agreement was observed between the theoretical and experimental data.

Electrospun polymeric nanohybrids with outstanding pollutants adsorption and electroactivity for water treatment and sensing devices

Graphene oxide (GO) and carbon nanotubes (CNTs) were loaded at different mutual ratios into poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-co-HFP) matrix and electrospun to construct mats that were assessed as smart sorbents for decontaminating water from methylene blue (MB) pollutant, while ensuring the additional possibility of detecting the dye amounts. The results revealed that sorption capacity enhances upon increasing GO content, which is beneficial to wettability and active area. Equilibrium adsorption of these materials is precisely predicted by the Langmuir isotherm model and the maximum capacities herein achieved, ranging from 120 to 555 mg/g depending on the formulation, are higher than those reported for similar systems. The evolution of the structure and properties of such materials as a function of dye adsorption was studied. The results reveal that MB molecules prompted the increase of electrical conductivity of the samples in a dose-dependent manner. Mats containing solely CNTs, while displaying the worst sorption performance, showed the highest electrical performances, displaying interesting changes in their electrical response as a function of the dye amount adsorbed, with a linear response and high sensitivity (309.4 µS cm−1 mg−1) in the range 0–235 µg of dye adsorbed. Beyond the possibility to monitor the presence of small amounts of MB in contaminated water and the saturation state of sorbents, this feature could even be exploited to transform waste sorbents into high-added value products, including flexible sensors for detecting low values of pressure, human motion, and so on.Graphical Multifunctional materials for dye absorption and detection, pressure sensing, fabricated by integrating GO and CNTs into PVDF-HFP matrix via electrospinning.

Effect of Plasma pretreatment and Graphene oxide ratios on the transport properties of PVA/PVP membranes for fuel cells

In this study, a novel proton-conducting polymer electrolyte membrane based on a mixture of polyvinyl alcohol (PVA)/polyvinyl pyrrolidone (PVP) (1:1) mixed with different ratios of graphene oxide (GO) and plasma-treated was successfully synthesized. Dielectric barrier dielectric (DBD) plasma was used to treat the prepared samples at various dose rates (2, 4, 6, 7, 8, and 9 min) and at fixed power input (2 kV, 50 kHz). The treated samples (PVA/PVP:GO wt%) were soaked in a solution of styrene and tetrahydrofuran (70:30 wt%) with 5 × 10−3 g of benzoyl peroxide as an initiator in an oven at 60 °C for 12 h and then sulfonated to create protonic membranes (PVA/PVP-g-PSSA:GO). The impacts of graphene oxide (GO) on the physical, chemical, and electrochemical properties of plasma-treated PVA/PVP-g-PSSA:x wt% GO membranes (x = 0, 0.1, 0.2, and 0.3) were investigated using different techniques. SEM results showed a better dispersion of nanocomposite-prepared membranes; whereas the AFM results showed an increase in total roughness with increasing the content of GO. FTIR spectra provide more information about the structural variation arising from the grafting and sulfonation processes to confirm their occurrence. The X-ray diffraction pattern showed that the PVA/PVP-g-PSSA:x wt% GO composite is semi-crystalline. As the level of GO mixing rises, the crystallinity of the mixes decreases. According to the TGA curve, the PVA/PVP-g-PSSA:x wt% GO membranes are chemically stable up to 180 °C which is suitable for proton exchange membrane fuel cells. Water uptake (WU) was also measured and found to decrease from 87.6 to 63.3% at equilibrium with increasing GO content. Ion exchange capacity (IEC) was calculated, and the maximum IEC value was 1.91 meq/g for the PVA/PVP-g-PSSA: 0.3 wt% GO composite membrane. At room temperature, the maximum proton conductivity was 98.9 mS/cm for PVA/PVP-g-PSSA: 0.3 wt% GO membrane. In addition, the same sample recorded a methanol permeability of 1.03 × 10−7 cm2/s, which is much less than that of Nafion NR-212 (1.63 × 10−6 cm2/s). These results imply potential applications for modified polyelectrolytic membranes in fuel cell technology.

Exploring the effect of polyacrylamide/graphene oxide composite hydrogel on the synthesis and application of ZSM-5 molecular sieves

Herein, we demonstrate the synthesis of coffin-shaped ZSM-5 molecular sieves in polyacrylamide (PAM)/graphene oxide (GO) composite hydrogel using the hydrothermal method. The as-synthesized products were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), and X-ray photoelectron spectroscopy (XPS), and Thermogravimetry analyses (TGA). The effect of PAM and GO addition on the morphology and structure of ZSM-5 was investigated. The results indicated that the introduction of PAM and GO promoted the growth of the ZSM-5 (101) plane. Moreover, samples synthesized in the PAM/GO hydrogel exhibited a longer c-axis and a more pronounced coffin-shaped morphology compared to samples synthesized solely in PAM hydrogel. The Si/Al ratio decreased with the addition of GO, possibly due to interface effects leading to the formation of ZSM-5 precursors with a higher Al content. TG, FT-IR, and XPS characterization revealed hydrogen bonding interactions between PAM and GO, and the addition of GO likely restricted the movement of polymers, improving cross-linking between monomers and forming a more uniform network structure. The sample G-15 (P-5) exhibited higher mesopore volume and average pore diameter, contributing to enhanced catalytic performance. However, with increasing GO content, the average pore diameter decreased, potentially due to functional groups on the surfaces of graphene oxide and polyacrylamide forming a more uniform and structurally stable three-dimensional network structure. This allowed for controlled modulation of the molecular sieve morphology and pore size. The introduction of PAM/GO hydrogel resulted in a moderate amount of weak acid and an increased amount of strong acid, both shifting to lower temperatures. The ZSM-5 molecular sieves synthesized in the PAM/GO composite hydrogel demonstrated outstanding MTO catalytic performance, exhibiting high selectivity for light olefins and an extended catalytic lifespan. This work is expected to provide new ideas and methods for developing efficient ZSM-5 catalysts.

Corrosion resistance of WC-Co-GO cemented carbides in NaCl solution

WC-Co cemented carbide with deferent content (0, 0.1 wt% and 0.3 wt%) of graphene oxide (GO) were prepared by hot-pressing sintering. The effect of added GO on the corrosion resistance of WC-Co cemented carbide in sodium chloride solution was investigated by electrochemical method. With the increase of GO content, the grain size of WC shows a decreasing trend. The research findings suggested that the added GO increased remarkably the corrosion potential and decreased the corrosion current density in sodium chloride solution. As the GO content increased from 0 to 0.1 wt% and 0.3 wt%, the charge-change resistance (Rct) first increased from 6393 to 9201 Ω·cm2 and then decreased to 7842 Ω·cm2, correspondingly. The characterization of corrosion surface by SEM, EDS and XPS indicated that GO acted as the physical barrier and enabled WC-Co cemented carbide to have a larger ratio of the surface area of the anode phase to the cathode phase, which improved the corrosion resistance.

Significantly different inhibition mechanisms of graphene oxide in laser-ignited combustion of micro and nano CL-20

Because of its high energy density, hexanitrohexaazaisowurtzitane(CL-20) has been widely used in propellants in place of conventional oxidizers. The adjustable burning rate of the CL-20 is a key factor in adapting the propellant to various environments. In this work, the effects of graphene oxide(GO) content on the thermal release, ignition and combustion characteristics of micro and nano CL-20 were thoroughly conducted based on the differential scanning calorimetry measurements (DSC), laser ignition, burning rate test and condensed combustion products collection. The results show GO has a positive effect on micro and nano CL-20 in ignition performance and a negative effect on combustion rate. Owing to the addition of GO, the original flameless combustion of CL-20 changes to flaming combustion. With increasing GO content, the burning rates of micro and nano CL-20 show completely different descending laws. Furthermore, the combustion mechanism of nano and micro CL-20/GO has been studied in detail. The burning rate of micro CL-20/GO is primarily determined by the condensed phase, and that of nano composite is controlled by both of the condensed and gas phases. This work provides a deeply insight into the influence mechanism of GO on the properties of nano and micro CL-20.

Self-healing nanocomposite hydrogels based on chitosan/ modified polyethylene glycol/graphene

The aim of this research is to prepare self-healing injectable nanocomposite hydrogels based on benzaldehyde-modified polyethylene glycol and chitosan, reinforced with graphene oxide (GO) for the delivery of pomegranate extract (PG) for hard tissue engineering. For this purpose, polyethylene glycol (PEG) was first modified by an aldehyde agent and mixed with chitosan to form hydrogels based on reversible Schiff-Base linkages. Nanocomposites were prepared with the addition of 0.5, 1.0, 1.5, and 2.0 wt% GO to the hydrogels. Then, PG was loaded into the final nanocomposite hydrogels as the drug model to promote cell proliferation and chondrogenesis. The scanning electron microscopy (SEM) images indicated that the incorporation of GO into the hydrogels increased the average pore size from 261 to 403 µm, resulting in a favorable porous structure. The results also showed an enhancement in the elastic properties as well as the compressive strength of the nanocomposite hydrogels with increasing GO content. The drug release profile followed a power-law kinetics, in which, the content of PG and GO affected the release rate. According to self-healing and injection tests, all the hydrogels had good injection and self-healing capabilities. The incorporation of GO into the hydrogel increased antibacterial properties to more than 99%. The in vitro assay indicated that PG loading provided a suitable environment for the growth and survival of cells on the hydrogels. Therefore, the designed system is a promising framework for the local delivery of pharmaceuticals for hard tissue engineering.

Influence of Raw Material Size on the Microstructure of Graphene Oxide and Its Early Strengthening Properties of Cemen

With the purpose of exploring the influence of raw material size on the structure-performance of graphene oxide (GO) for cement reinforcement, this paper used natural flaked graphite with different particle sizes as raw material to prepare GO nanosheets by a method of enhanced Hummers, and then used scanning electron microscope (SEM) , X-ray diffraction (XRD) , Raman spectrum, infrared spectrum (IR) and other means to characterise the microstructure of GO products in detail, and then investigated the effects of raw material size and graphene oxide GO dosage on its early strengthening effect in cement. The experimental results showed that with the decrease of raw material particle size, the spacing between the layers of GO products is basically the same, while the oxidization degree is increased, and the oxygen-containing groups on the surface are increased. When the GO matt was used to prepare cement mortar with same GO extent, the mechanical strengths at an age of 3 days were found to initially increase and then decrease with the reduction of raw material particle size, and the GO products had the best effect on the improvement of early mechanical strength of cement when the raw material particle size was 13μm. On the other hand, GO matt being obtained from the raw material particles in a size of 13μm was employed to prepare cement mortar with different GO content, of which the 3d strength was found to increase apparently with the increasing GO content, and thus resulted in the increment of 8. 85% to the 3d compressive strength and 6. 34% to the 3d flexural strength for the mortar specimen obtained with a GO content of about 0. 05%, but the further increasing of the GO content is not proposed, which might gave rise of a relative low mechanical strength.

Ultrasonic Spray Deposited CdS-GO Composite Films for Solar Cell Applications

In the present study, the synthesis and characterization of cadmium sulfide (CdS) and graphene oxide (GO) composite films are investigated. These films have the potential to be utilized in solar cell applications due to their unique optical and electric properties. A chemical bath deposition was used to prepare the CdS thin films, while the hammer method was used to synthesize GO sheets. In this comparative study, spray deposition was used to prepare CdS-GO composite films with different ratios of CdS to GO. The spray deposition method used in this study offers a simple and cost-effective way to prepare large-area films for practical applications. The structural, and optical, properties of the composite films were characterized using X-ray diffraction, scanning electron microscopy, and UV-Vis spectroscopy measurements. The results show that the CdS-GO composite films exhibit enhanced optical properties as compared to the pure CdS films. The band gap energy of the composite films decreased with increasing GO content, indicating improved optical properties. These findings suggest that CdS-GO composite films have the potential for use in solar cell applications. I-V characteristics were obtained using a solar cell tester kit to analyse the applications of fabricated conducting films in the field of solar cells.

A highly sensitive paper-based chipless RFID humidity sensor based on graphene oxide

In this paper, a highly sensitive paper-based humidity sensor is designed and fabricated to overcome the typically low sensitivity and small quality factor of paper-based chipless radio-frequency identification (RFID) humidity sensors. A toroidal inductor-interdigitated electrodes (IDE) capacitor is used as the resonator structure of the new sensor, and the structural parameters of the sensor are optimized using the software of high frequency structure simulator (HFSS) to improve the quality factor. Three paper-based sensor samples were fabricated via screen printing using regular printing paper, Kodak photo paper, and double-sided copper-coated paper as the substrate. In addition, the resonance characteristics, sensitivity, recovery characteristics, stability and other sensor performances were tested. The results show that the sensitivity of the copper-coated-paper-based sensor is significantly better than the two other paper-based sensors. The simulation and test results of the moisture-sensitive characteristics are consistent for graphene oxide (GO) films, which were prepared using the spray method on the surface of the copper-coated-paper-based sensor with mass concentrations of 1 mg/mL, 2 mg/mL, and 5 mg/mL. This indicates that GO films can significantly improve sensor sensitivity when combined with paper-based moisture sensing. Furthermore, the sensitivity increases with increasing GO concentration, the 5 mg/mL GO sensor show a sensitivity of 6.25 MHz/%RH and a range of 60% RH-90% RH. The 1 mg/mL GO humidity sensor shows good recovery characteristics (92.4% recovery). Based on the presence of hydrophilic functional groups in the GO material, a moisture sensing mechanism that GO could improve the sensitivity of the sensor is analyzed.

Graphene Oxide Incorporated Zinc Oxide Thin Films by Spray Pyrolysis for Efficient Photodegradation of Methylene Blue

AbstractPhotodegradation of methylene blue dye was studied with pure and graphene oxide incorporated zinc oxide thin films as catalysts. Graphene oxide content in the precursor solution was varied from 0.0005 to 0.005 g/L. Thin films were prepared by automated spray pyrolysis technique at a substrate temperature of 425 °C. Structural studies revealed the formation of hexagonal wurtzite structure of zinc oxide. Carbon presence in the films was confirmed with energy‐dispersive spectroscopy. Optical band gap of the samples was determined using Tauc method. Intensity of the near band emission of photoluminescence spectrum was found to decrease upon increasing graphene oxide concentration. Photocatalytic activity of all the films has been studied against methylene blue dye under solar irradiation for 180 minutes and it is found that the highest graphene oxide content attributes to better degradation efficiency of 91.2 %.

Influence of graphene oxide on the dielectric properties of biogenically synthesized ZnO nanoparticles

This study presents a novel and biogenic route to synthesize zinc oxide (ZnO) nanoparticles using Phoenix dactylifera fruit extract as a plant-mediated reducing agent. Graphene oxide (GO) was synthesized using the improved Hummer's method, and a series of GO-ZnO nanocomposites were produced by the ultrasonic-dispersion method. The structural and optical properties of the nanocomposites have been analyzed using XRD, TEM, FESEM-EDX, UV-vis. DRS, and FTIR spectroscopy. The results indicate that ZnO nanoparticles are deposited over GO sheets in the nanocomposites. The structural analysis and Rietveld refinement confirmed the successful synthesis of crystalline single-phase ZnO nanoparticles with a hexagonal-wurtzite structure. The influence of GO on the dielectric properties of green-synthesized ZnO nanoparticles was analyzed in the frequency range 20 Hz-2 MHz at ambient temperature. The results showed a significant increase in the dielectric constant and ac conductivity with growing GO content in the nanocomposites compared to that of pristine ZnO. Complex impedance analysis revealed the non-Debye type relaxation and a decreasing trend in the complex impedance value with increasing GO content. This novel biogenic synthesis approach is energy-efficient and environment-friendly, which can provide an effective route for low-cost and scaled-up production of nanocomposites for several applications.

Effect of Graphene Oxide on the Mechanical Property and Microstructure of Clay-Cement Slurry.

As a widely used material in underground engineering, clay-cement slurry grouting is characterized by poor initial anti-seepage and filtration capacity, low strength of the resulting stone body, and a tendency to brittle failure. In this study, a novel type of clay-cement slurry was developed by adding of graphene oxide (GO) as a modifier to ordinary clay-cement slurry. The rheological properties of the improved slurry were studied through laboratory tests, and the effects of varying amounts of GO on the slurry's viscosity, stability, plastic strength, and stone body mechanical properties were analyzed. The results indicated that the viscosity of clay-cement slurry increases by a maximum of 163% with 0.05% GO, resulting in a decrease in the slurry's fluidity. The stability and plastic strength of GO-modified clay-cement slurry were significantly enhanced, with the plastic strength increasing by a 5.62 time with 0.03% GO and a 7.11 time with 0.05% GO at the same curing time. The stone body of the slurry exhibited increased uniaxial compressive strength and shear strength, with maximum increases of 23.94% and 25.27% with 0.05% GO, respectively, indicating a significant optimization effect on the slurry's durability. The micro-mechanism for the effect of GO on the properties of slurry was investigated using scanning electron microscopy (SEM) and a diffraction of X-rays (XRD) test. Moreover, a growth model of the stone body of GO-modified clay-cement slurry was proposed. The results showed that after the GO-modified clay-cement slurry was solidified, a clay-cement agglomerate space skeleton with GO monolayer as the core was formed inside the stone body, and with an increase in GO content from 0.03% to 0.05%, the number of clay particles increased. The clay particles filled the skeleton to form a slurry system architecture, which is the primary reason for the superior performance of GO-modified clay-cement slurry when compared with traditional clay-cement slurry.

Regulation of bimodal structure and mechanical properties of powder-thixoformed GO/ZK60 magnesium matrix composite through adjusting GO content

Although remarkable strength enhancements can be achieved in graphene oxide (GO)/ graphene nanoplatelets (GNPs) reinforced Mg matrix composites by using the available techniques, their ductility is always quite poor due to the difficultly avoided strength-ductility trade-off. To conquer this dilemma, GO/ZK60 composites with bimodal-grain structure were fabricated using powder thixoforming in this work. The results indicate that the grain size and volume fraction of coarse grains (CGs) first decrease as the GO content increases to 0.2 wt.% and then increase again as the content increases to 0.3 wt.%, while the grain size in the fine grains (FGs) almost does not change. Consequently, the strength of the composites is improved with increasing GO content and reaches the peak values at the content of 0.2 wt.%. The composite with 0.1 wt.% GO content exhibits significantly increased tensile yield strength up to 177 ± 2 MPa while maintaining a high elongation of 23.1% ± 2.5%, being equivalent to that of the ZK60 matrix alloy. The increased FGs volume fraction, together with the promoted dislocation accumulation and storage via GO and grain refinement of large-sized CGs lead to the improvement of strain hardening ability, thus rendering the composite an excellent ductility. Furthermore, the deformation of the GO/ZK60 composites occurs progressively from the FGs to the CGs, which is opposite to the status of the milled ZK60 matrix alloy. In view of the microstructure characteristics of the composites, a new complex calculation model was proposed and it could well predict the strength of the bimodal GO/ZK60 composites. This study provides a new insight into the microstructure design and fabrication technology of GO/GNPs reinforced metal-based composites with high strength and ductility.

Tuning the micro‐structure, laser ignition, and isovolumetric burning performance of nitrocellulose propellant via incorporation of graphene oxide

AbstractNanoscale recombination between carbon nanomaterials (CNs) and polymers has been proposed for a variety of industrial and scientific applications. Composite energetic materials consisting of CNs with novel laser ignition property and tunable combustion performance have attracted people's attention. Here, reported is the novel manufacturing process of uniform nitrocellulose (NC)/graphene oxide (GO) nanocomposite propellant and the micro‐structure, laser ignition and isovolumetric burning features of the propellants introduced by GO. The results of microstructure tests indicated that GO (0.25–2 wt%) was stripped and dispersed homogeneously and dense nanocomposite propellants were prepared successfully through water ultrasonic dispersion, twin‐screw mixture, as well as compression molding. The crystallization of NC was forbidden by doping GO, meanwhile, the thermal stability and thermal conductivity of the composite propellants increased slightly with the addition of GO. The results of laser ignition combustion experiments showed that GO was an efficient additive to shorten the ignition delay time from more than 2000–14 ms when 2 wt% of GO was doped, however, the combustion flame intensity was also weakened due to the addition of GO. The combustion tests in a closed bomb vessel were conducted, and the results showed that GO would not affect the stable combustion of NC at high combustion pressure, moreover, the burning rate and dynamic vivacity of the composite propellants decreased with the increase of GO content.

Recoverable cellulose composite adsorbents for anionic/cationic dyes removal

GO/HEC/PGDE/Fe3O4 materials were successfully fabricated using environmentally-friendly hydroxyethyl cellulose (HEC), poly(ethylene glycol) diglycidyl ether (PGDE), graphene oxide (GO) and magnetic Fe3O4. Systematic investigations were completed to explore the influences of GO content in GO/HEC/PGDE/Fe3O4 and adsorption conditions on the adsorptions of cationic dyes (methylene blue (MB), crystal violet (CV)) and anionic dye acid blue 25 (AB-25). The increase of GO content can remarkably improve the adsorption capacity of GO/HEC/PGDE/Fe3O4 for the dyes. The three kinetic, four isothermic and three thermodynamic models were investigated to reveal the adsorption behaviors of the dyes. The formation of HEC/PGDE/Fe3O4 and adsorption mechanisms of the dyes by GO/HEC/PGDE/Fe3O4 were suggested. The GO/HEC/PGDE/Fe3O4 endowed with easy-fabrication, eco-friendly feature, efficient adsorption capacity of anionic/cationic dyes, convenient separation and reusability has potential applications in wastewater purification industry.