Mechanical and high velocity impact performance of a hybrid long carbon/glass fiber/polypropylene thermoplastic composite

This research explores mechanical and high velocity impact response of hybrid long carbon/glass fiber-reinforced polypropylene thermoplastic composites (HLFT) with different fiber lengths. The work examines three hybrid long fiber thermoplastic composites, i.e., 5, 10 and 20 mm. The HLFTs were prepared by a combination of extrusion and pultrusion processes and using a cross-head die. Tensile and Izod impact tests were carried out to evaluate the mechanical performance of each HLFT compound. A gas gun with a spherical projectile was used to conduct high velocity impact tests at three velocities of 144, 205 and 240 m/s. The results showed that internal mixing operation caused extensive reduction in fiber length of all three LFT lengths. Tensile strength, modulus and Izod impact test results were the indications of higher values with increase in HLFT length. Comparison of these results for the HLFT with that of corresponding glass/PP LFTs, adopted from earlier work by Shayan Asenjan et al. (J Compos Mater 53:353–360, 2019), showed better performance of HLFT. The high velocity impact results showed a steady higher impact performance with the increase in HFLT fiber length for all impact velocities tested. Comparison of HLFT high velocity impact performance revealed better results for all impact velocities tested with that of the corresponding glass/PP LFT composite.     

Electrocatalytic oxidation of formic acid and formaldehyde on platinum nanoparticles decorated carbon-ceramic substrate

Electrochemical characteristics of formic acid (FM) and formaldehyde (FM) oxidation on a potent catalyst, platinum nanoparticles supported on carbon-ceramic substrate (CC/Pt), were investigated via cyclic voltammetric and chronoamperometric analysis in mixed 0.75 M FM (or 0.75 M FM) and 0.1 M H₂SO₄ solutions. The results were compared to those at a polycrystalline platinum electrode and platinum particles deposited on platinum and glassy carbon electrodes. It was found that CC/Pt was catalytically more active than smooth platinum and platinum particles supported on platinum and glassy carbon electrodes. On the other hand, such nanoparticles on CC substrate exhibit better catalytic behavior towards FA and FM than the corresponding platinum and glassy carbon electrodes, which is raised form high porosity of CC substrate for better distribution of platinum particles and to produce of platinum particles in nano size. The effect of some experimental factors was studied and optimum conditions were suggested. Finally, the long-term stability of the modified electrode has also been investigated. These results indicate that the system studied in the present work is the most promising system for use in fuel cells.     

Studying the effect of particle size on the antibacterial activity of some N-nicotinyl phosphoric triamides

Using ultrasonic top-to-down method, nanoparticles of two N-nicotinyl phosphoric triamides: C₅H₄NC(O)NHP(O)R, R?=?4-CH₃-NC₅H₁₀ (1), (CH₃)₃CNH₂ (2) were prepared for the first time and characterized by ³¹P, ¹³C, ¹H NMR, FTIR, scanning electron microscopy, energy dispersive X-ray. The average particle size of 1 and 2 were 60–70 and 40–50?nm, respectively, and the morphology was spherical for 1 and rod for 2. Solid state (powder) antibacterial effect of these compounds and two other similar reported ones, in their macro- and nanosizes, were evaluated with colony counting method on one Gram-positive (Staphylococcus aureus) and one Gram-negative (Escherichia coli) bacteria in Brain–Heart infusion culture medium. Results showed that all the macro- and nanosized compounds, except macrosized 1, were antibacterial and all nanoscaled ones had stronger antibacterial activity than their macroscaled analogues. The most effect of the particle size was observed for 1: by decreasing the particle sizes, the antibacterial activity state of 1 was changed from inactive (for macro) to potent (for nano).     

Multilayered Electrospun/Electrosprayed Polyvinylidene Fluoride+Zinc Oxide Nanofiber Mats with Enhanced Piezoelectricity

Electrospun polyvinylidene fluoride (PVDF) nanofibers have been widely used in the fabrication of flexible piezoelectric sensors and nanogenerators, due to their excellent mechanical properties. However, their relatively low piezoelectricity is still a critical issue. Herein, a new and effective route to enhance the piezoelectricity of PVDF nanofiber mats by electrospraying zinc oxide (ZnO) nanoparticles between layers of PVDF nanofibers is demonstrated. As compared to the conventional way of dispersing ZnO nanoparticles into PVDF solution for electrospinning nanofiber mats, this approach results in multilayered PVDF+ZnO nanofiber mats with significantly increased piezoelectricity. For example, 6.2 times higher output is achieved when 100% of ZnO (relative to PVDF quantity) is electrosprayed between PVDF nanofibers. Moreover, this new method enables higher loading of ZnO without having processing challenges and the maximum peak voltage of ≈3 V is achieved, when ZnO content increases up to 150%. Additionally, it is shown that the samples with equal amount of material but consisting of different number of layers have no significant difference. This work demonstrates that the proposed multilayer design provides an alternative strategy to enhance the piezoelectricity of PVDF nanofibers, which can be readily scaled up for mass production.     

Preparation and characterization of water-based polyurethane–acrylic hybrid nanocomposite emulsion based on a new silane-containing acrylic macromonomer

A new silane-containing acrylic macromonomer, maleimidedoethoxybutoxydimethylsiloxy butyl acrylate (MEBDMSBA), based on maleic anhydride (MA), ethanolamine (EA), 1,4-butanediol (BDO), dichlorodimethylsilane (DCDMS), and acrylic acid (AA) has been synthesized for formulation of waterborne polyurethane (WPU). Also a series of new silane-containing WPU, methyl methacrylate (MMA), MEBDMSBA, and montmorillonite (MMT) with organically modified montmorillonite (OMMT) content (1.25 wt%) hybrid nanocomposites have been successfully prepared by the emulsion polymerization in the presence of a WPU dispersion, using ammonium peroxodisulfate (APS) as an initiator. The WPU dispersion has been synthesized by a polyaddition reaction of isophorone diisocyanate (IPDI) on polypropylene glycol (PPG-1000) and dimethylol propionic acid (DMPA) as chain extender. The monomer was characterized by Fourier transformer infrared spectroscopy (FTIR), elemental analysis, proton (¹H NMR), and carbon (¹³C NMR) nuclear magnetic resonance spectroscopes, respectively. The nanocomposite emulsions were also characterized using Fourier transform infrared spectroscopy (FTIR) and laser light scattering. Thermal properties of the copolymers were studied using thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The OMMT was characterized by FTIR and X-ray diffraction (XRD). The morphology of copolymers was investigated by scanning electron microscopy (SEM) and transition electron microscopy (TEM), and then the effects of silane concentrations on the water absorption ratio were examined. Results showed that OMMT could improve the properties of emulsion; in other words, the properties of nanocomposite emulsion were better when compared with those of the silane–acrylate emulsion.     

Laccase‐catalyzed synthesis of polypyrrole‐multiwalled carbon nanotube composites as energy storage materials for capacitors

Multiwalled carbon nanotubes (MWNTs) were coated with polypyrrole (PPy) using in situ enzymatic polymerization of pyrrole catalyzed by a laccase (benzenediol:oxygen oxidoreductase, EC 1.10.3.2) from Trametes versicolor. Transmission electron microscopy revealed that the MWNTs were uniformly coated with very thin layers of PPy without any indication of globular polymer aggregate formations. The enzymatic synthesis of the MWNTs/PPy composites was quite simple being performed in a one‐pot aqueous solution (pH 4.0) under mild reaction conditions. The potential of the composites with respect to the development of energy storage devices was demonstrated by fabricating a two‐electrode coin cell capacitor (diameter 20 mm, thickness 1.6 mm) utilizing the composites as electrode materials. The capacitance of the cell was 28.0 F g^?1 for the electrode material as measured by a galvanostatic charge–discharge method. The energy density and power density were 2.55 and 805 W kg^?1, respectively, which were close to those of the capacitors classified as ultracapacitors. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43307.     

A benzoate coprecipitation route for synthesizing nanocrystalline GDC powder with lowered sintering temperature

Electrolyte powders with low sintering temperature and high-ionic conductivity can considerably facilitate the fabrication and performance of solid oxide fuel cells (SOFCs). Gadolinia-doped ceria (GDC) is a promising electrolyte for developing intermediate- and low-temperature (IT and LT) SOFCs. However, the conventional sintering temperature for GDC is usually above 1200 °C unless additives are used. In this work, a nanocrystalline powder of GDC, (10 mol% Gd dopant, Gd_0.1Ce_0.9O_1.95) with low-sintering temperature has been synthesized using ammonium benzoate as a novel, environmentally friendly and cost-effective precursor/precipitant. The synthesized benzoate powders (termed washed- and non-washed samples) were calcined at a relatively low temperature of 500 °C for 6 h. Physicochemical characteristics were determined using thermal analysis (TG/DTA), Raman spectroscopy, FT-IR, SEM/EDX, XRD, nitrogen absorptiometry, and dilatometry. Dilatometry showed that the newly synthesized GDC samples (washed and non-washed routes) start to shrink at temperatures of 500 and 600 °C (respectively), reaching their maximum sintering rate at 650 and 750 °C. Sintering of pelletized electrolyte substrates at the sintering onset temperature for commercial GDC powder (950 °C) for 6 h, showed densification of washed- and non-washed samples, obtaining 97.48 and 98.43% respectively, relative to theoretical density. The electrochemical impedance spectroscopy (EIS) analysis for the electrolyte pellets sintered at 950 °C showed a total electrical conductivity of 3.83 × 10^?2 and 5.90 × 10^?2 S cm^?1 (under air atmosphere at 750 °C) for washed- and non-washed samples, respectively. This is the first report of a GDC synthesis, where a considerable improvement in sinterability and electrical conductivity of the product GDC is observed at 950 °C without additives addition.     

Curcumin Attenuates Environment-Derived Osteoarthritis by Sox9/NF-kB Signaling Axis

Inflammation has a fundamental impact on the pathophysiology of osteoarthritis (OA), a common form of degenerative arthritis. It has previously been established that curcumin, a component of turmeric (Curcuma longa), has anti-inflammatory properties. This research evaluates the potentials of curcumin on the pathophysiology of OA in vitro. To explore the anti-inflammatory efficacy of curcumin in an inflamed joint, an osteoarthritic environment (OA-EN) model consisting of fibroblasts, T-lymphocytes, 3D-chondrocytes is constructed and co-incubated with TNF-α, antisense oligonucleotides targeting NF-kB (ASO-NF-kB), or an IkB-kinase (IKK) inhibitor (BMS-345541). Our results show that OA-EN, similar to TNF-α, suppresses chondrocyte viability, which is accompanied by a significant decrease in cartilage-specific proteins (collagen II, CSPG, Sox9) and an increase in NF-kB-driven gene proteins participating in inflammation, apoptosis, and breakdown (NF-kB, MMP-9, Cox-2, Caspase-3). Conversely, similar to knockdown of NF-kB at the mRNA level or at the IKK level, curcumin suppresses NF-kB activation, NF-kB-promotes gene proteins derived from the OA-EN, and stimulates collagen II, CSPG, and Sox9 expression. Furthermore, co-immunoprecipitation assay shows that curcumin reduces OA-EN-mediated inflammation and chondrocyte apoptosis, with concomitant chondroprotective effects, due to modulation of Sox-9/NF-kB signaling axis. Finally, curcumin selectively hinders the interaction of p-NF-kB-p65 directly with DNA—this association is disrupted through DTT. These results suggest that curcumin suppresses inflammation in OA-EN via modulating NF-kB-Sox9 coupling and is essential for maintaining homeostasis in OA by balancing chondrocyte survival and inflammatory responses. This may contribute to the alternative treatment of OA with respect to the efficacy of curcumin.