Evaluation of the Effect of Nanosilica on Thermal and Mechanical Properties of Metal–Metal and Metal–Glass Canola-Based Polyurethane/Nanosilica Adhesives

Nanocomposites with different concentration of nanofiller were prepared by adding nanosilica to the canola-based polyurethane matrix via in situ polymerization. The effect of nanosilica on the mechanical properties of adhesives was evaluated by tensile tests. Adhesive characteristics on metal–metal and metal–glass bondings were also evaluated by lap shear strength tests. Incorporation of nanosilica into the canola-based polyurethane enhanced both tensile and lap shear strength of synthesized adhesives. Also the effect of nanoparticles on glass transition temperature and thermal stability was investigated by differential scanning calorimetry and thermogravimetric analysis, respectively. The increase of nanosilica content in the polyurethane adhesives, thermal property of the nanocomposites improved.     

Measurement of Glass–Rubber Transition Temperature of Skim Milk Powder by Static Mechanical Test

Abstract

Stickiness behavior of skim milk powder was investigated based on the mechanical property of the material during the glass–rubber transition. A thermally controlled device was developed for the static mechanical test. This device was attached to a texture analyzer, and skim milk powder, which was used as a model sample, was tested for its glass–rubber transition temperature (T_g-r) using static compression technique (creep test). Changes in compression probe distance as a function of temperature were recorded. T_g-r was determined, in the region where changes in the probe distance were observed, by using linear regression technique. The effect of sample quantity, compression force, and heating rate on the determination of T_g-r was investigated. All these parameters significantly influenced the T_g-r determination (p < 0.05). The T_g-r of skim milk powder measured by this novel technique was found closely correlated to its glass transition temperature (T_g) measured by DSC.     

Detonation Properties and Electrical Conductivity of Explosive–Metal Additive Mixtures

Detonation properties of mixtures of condensed high explosives with metal additives are studied. A scheme of measurement of high electrical conductivity of detonation products ( > 10 ^–1 · cm^–1) with a time resolution of 10 nsec is developed. It is shown that the properties of detonation products depend significantly on the content of the additive in the HE and on dispersion and density of the mixture. The electrical conductivity of detonation products of the compositions examined reaches 5 · 10^{3 –1} · cm^–1, which is more than three orders higher than the electrical conductivity of the HE without the additive. Significant variation of electrical conductivity of detonation products over the conducting region thickness has been found. The main conductivity corresponds to a sector 1 mm long near the detonation front. The overdriven state of the detonation wave has a strong effect on electrical conductivity and conducting region thickness. It is assumed that the behavior of electrical conductivity with time is caused by successive processes of shock compression of the HE, excitation of the chemical reaction (including the reaction of the additive with detonation products), and expansion of detonation products. The measurement technique used is highly informative due to the possibility of studying detonation in various regimes.     

Enhancement of the electrooxidation of ethanol on a Pt–PEM electrode modified by tin. Part I: Half cell study

The direct platinisation of a solid polymer electrolyte (Nafion^® membrane) was realized by chemical reduction of a platinum salt. The Pt–PEM electrodes thus obtained were modified by tin to improve the electrocatalytic activity towards the electrooxidation of ethanol. The Pt–PEM and Pt–Sn–PEM electrodes were characterized by TEM, EDX and XRD analysis, cyclic voltammetry, and their polarisation curves for the electrooxidation of ethanol were determined under quasisteady state conditions.     

Size-Selective Homocoupling of Arylboronic Acids Mediated by a Copper-Based Metal–Organic-Framework

Copper-based metal–organic-frameworks with open metal sites have received increasing research interest as heterogeneous catalysts for various organic transformations. A copper-based metal organic framework (1) built with L-NO₂ ligand (L-NO₂?=?4,4′-dicarboxy-4″-nitrotriphenylamine) was selected for catalyzing aerobic homocoupling of arylboronic acid toward biaryl products given its structural robustness and 1-D channels lined with rich open metal sites. The experimental results show that MOF (1) exhibits pronounced size selectivity over arylboronic acid molecules, which is only effective for short arylboronic acid molecules (e.g. phenylboronic acid, p-methylphenylboronic acid and p-fluorophenylboronic acid), giving the corresponding biaryl products in good yields. Moreover, MOF (1) also demonstrates a good recyclability which only shows a small decay in the catalytic performance after five repeated runs.

     

Organic–Inorganic Composite Material Polyaniline Ce(IV) molybdate: Thermal and Room Temperature Electrical Conductivity Measurement Studies

An electrically conducting ‘organic–inorganic’ composite material polyaniline Ce(IV) molybdate was prepared by incorporating electrically conducting polymer, i.e., polyaniline into inorganic precipitate of polyvalent metal acid salts i.e., Ce(IV) molybdate. The temperature dependence of electrical conductivity of this composite system with increasing temperatures was measured on compressed pellets by using a 4-in-line-probe dc electrical conductivity-measuring instrument. The values of conductivity lies in the semiconductor region, i.e., they are of the order of 10⁻⁵–10⁻² S cm⁻¹ and obey the Arrhenius equation. The thermal stability of this composite material in terms of dc electrical conductivity retention was studied under isothermal and cyclic techniques and electrical conductivity of composite was found to be sufficiently stable under ambient temperature conditions. The dependence of the electrical conductivity prepared with different concentrations of aniline monomers, on the concentration of conducting phases i.e., polyaniline was showed that electrical conductivity increase followed the percolation threshold.     

Thermal effects of a laser beam on the electrodeposition of Ni–P alloys

The paper deals with the effects of an incident laser beam on electrodeposition of Ni–P alloys from dilute acetate solutions. The kinetics of separate reductions of Ni2+ and H2PO?2 species were first investigated by linear sweep voltammetry, varying the hypophosphite concentration and the solution temperature: comparison of the kinetically limited current densities of the two reductions suggested that increasing temperature might reduce the significance of P codeposition. This tendency was confirmed by deposition runs carried out at controlled current. Deposition performance was discussed in terms of faradaic yield and deposit properties, namely P content together with the aspect and the structure of the alloys. Use of a continuous or pulsed laser beam was shown to reduce the P content in the deposit at high current densities; in some cases, amorphous structures were replaced by more crystalline forms with assistance of a laser beam.     

Entropy Similarity of the Thermal Diffusion Properties of a Nitrogen–Argon Gas Mixture

The molecular thermal diffusion characteristics of a frozen nitrogen–argon binary gas mixture at normal pressure are calculated by the entropy similarity method over wide ranges of temperature and concentration. The calculated results agree satisfactorily with experimental data.     

Thermal Conductivity of Diamond Films: 0.5 μm to 0.5 mm

A review of the thermal properties of chemical-vapor-deposited (CVD) diamond ranging in thickness from 0.5 μm to 0.5 mm is presented. The typical columnar microstructure of the material has a strong influence on the thermal properties, causing a steep gradient in both the in-plane (κ_‖) and normal (κ_⊥) conductivities, as well as considerable anisotropy. Data for κ_‖ from above room temperature down to liquid helium temperatures for high-quality thick samples has revealed several types of phonon scattering centers preferentially located along grain boundaries. This model of dirty grain boundaries provides a framework for understanding the conductivity of thinner, lower-quality material. The general difficulty of identifying microscopic sources of thermal resistance in CVD diamond is discussed, especially in view of the tendency for the concentrations of many types of defects to be highly correlated with each other. Finally, recent work on interfacial resistance between CVD diamond and Si substrate shows that the columnar microstructure has a strong influence for high-quality films as thin as 2 μm.     

Improvement of a cementation process by ultrasound: case of the cadmium–zinc couple at a RDE

This paper describes the impact of low frequency (20kHz) ultrasound (US) on Cd(II)/Zn cementation implemented on a RDE geometry. With and without US the reaction is mass-transfer controlled with two-step first-order kinetics mainly connected to deposit evolution. US improves the kinetics but to a lower extent than expected from electrochemical Cd(II) reduction. The favourable turbulence enhancement due to the deposit without US is not present when applying US because the deposit is continually removed from the surface. The influence of parameters such as temperature, initial concentration of reactants and US power is also analysed.     

An Increase in the Refractive Index of a Multicomponent Silicate Glass by Six-Hundredths upon the Na+glass–Li+meltIon Exchange

An increase in the refractive index of the glass surface by n= 0.06 after the Na⁺ _glass–Li⁺ _meltion exchange is obtained for the first time.     

Synthesis of Novel Double-Layer Nanostructures of SiC–WO x by a Two Step Thermal Evaporation Process

A novel double-layer nanostructure of silicon carbide and tungsten oxide is synthesized by a two-step thermal evaporation process using NiO as the catalyst. First, SiC nanowires are grown on Si substrate and then high density W₁₈O₄₉ nanorods are grown on these SiC nanowires to form a double-layer nanostructure. XRD and TEM analysis revealed that the synthesized nanostructures are well crystalline. The growth of W₁₈O₄₉ nanorods on SiC nanowires is explained on the basis of vapor–solid (VS) mechanism. The reasonably better turn-on field (5.4 V/μm) measured from the field emission measurements suggest that the synthesized nanostructures could be used as potential field emitters. Hyeyoung Kim and Karuppanan Senthil contributed equally to this article.     

Targeted Highly-Thermostable Metal–Organic Frameworks Directed by Imidazole: Syntheses, Structures, Thermal Behaviors and Luminescent Properties

Three new isostructural 3D lanthanide MOFs (Ln(HBPTC)(H₂O)) (Ln = Tb (1), Pr (2), Nd (3); H₄BPTC = 3,3′,4,4′-biphenyltetracarboxylic acid) have been synthesized under hydrothermal conditions using imidazole as a structure-directing agent, and characterized by elemental analyses, IR, thermogravimetric analyses (TGA) and powder X-ray diffraction (PXRD) analyses. Topologically, compounds 1–3 demonstrate an intriguing 3D (6, 6)-connected network with the Schläfli symbol of (4¹⁰·6⁵)(4⁹·6⁶); and if the dinuclear (Ln₂) clusters are considered as the single 8-connected nodes, they can be described as a scarcely reported (4, 8)-connected alb net constructed from two intertwining sqp-4 nets. TGA and PXRD analyses reveal that compounds 1–3 exhibit high thermal stability, at least being stable up to 410 °C. Furthermore, the luminescence studies were performed on compound 1 and its dehydrated phase in the solid state at room temperature. The results demonstrate that compound 1 displays intense green emission, implying its potential application as fluorescence material. And the luminescence of 1 is quenched when removing the coordinated water molecules.     

Passage of the Roughening Temperature Influence on the Crystalline Structure and Morphology of a Nano Metal–Organic Material

The reactions between 2-mercaptobenzothiazole (HMBT) and AgNO₃ in ultrasonic bath with low and high concentrations of initial reagents provided yellow precipitates of [Ag₆(MBT)₆] (1), which can be considered as 1L and 1H, respectively. Powder XRD patterns of them showed that they have crystalline structure and SEM images of 1L and 1H approved that microblocks and nanosheets of 1 were formed, respectively. Similar studies after mechanical and thermo-mechanical treatment of 1L and 1H indicated that compound 1 with nanoparticle and agglomerated nanoparticle morphologies were obtained. As a result of heat and energy created from the friction process and also external heat source a roughening transition was occurred and the crystalline samples of 1L and 1H, loses their facets. This can be understood by considering compound 1 surface above the roughening temperature as a liquid surface.     

An inequality for the empirical D.F. in the non–I.I.D. case

A generalization to the non-i.i.d. case of an inequality for the empirical df. due to Mason (1981) is proved     

Thermal and Mechanical Properties of Glass–Ceramics Based on Slate and Natural Raw Materials

Silicon - In recent years, utilization of raw materials was increased to produce natural low-cost glass–ceramic materials with distinct properties and appropriate for various applications....     

Heavy Metal Ion Sorption Properties of Porous Glass Beads with a Core‐Shell Structure

Porous glass beads with a core‐shell structure have been successfully prepared through subcritical water treatment. The product has high capacity and fast mass transfer property due to its structure, and may serve as an inorganic adsorbent. Accordingly, the kinetics, the equilibrium isotherm, and the column breakthrough curve of this material were measured using Cu(II) as a model target ion. The results indicate that the material has an advantage over some other adsorbents, such as kaolinite and clinoptilolite, in both adsorption capacity and kinetics. The adsorption capacity for Cu(II) is almost twice as much as that of the Na‐mordenite. The pseudo‐second order kinetic and the Langmuir isotherm fit the experimental data. An adsorption mechanism was hypothesized in which the non‐bridging oxygen ions in the glass network were hypothesized to be the functional site.