Search results

In the textile industry, liquid ammonia treatment is an important way to modify the structure of natural fibers. The purpose of this paper is to reveal the diffusion behaviors of liquid ammonia in cellulose.

To analysis the diffusion behaviors of liquid ammonia in cellulose, the cellulose model and the system of ammonia and cellulose are built. Infrared spectrum is carried out to test the model of cellulose, which is found to agree with experiment. Diffusion coefficients, free volume and hydrogen bonds are discussed to explain diffusion behaviors.

The results demonstrate that diffusion coefficients and free volume of systems rise with increasing temperature. The diffusion coefficients of ammonia are larger than those of water, a result in agreement with free volume. To understand the mechanism of diffusion, the numbers of hydrogen bonds are tracked. It is found that without ammonia, intrachain hydrogen bonds decrease with the increase of temperature, which indicate that the structural stability of cellulose is deteriorated. And the increased interchain hydrogen bonds show that swelling properties of cellulose become better with the increase of temperature. After ammonia treatment, the numbers of intrachain hydrogen bonds remain stable, indicating that the structure stability of cellulose chain is maintained. But, there is a substantial rupture of interchain hydrogen bonds, ammonia molecule destroys the hydrogen bond network between the original cellulose molecular chains, which intensifies the activity of cellulose molecular chains and enlarges the distance between cellulose molecular chains, showing good swelling properties.

The research findings give a detailed information about the diffusion behaviors of liquid ammonia in cellulose, which provide the theoretical evidence for liquid ammonia treatment.

The chemical structure of paper is simply explained, commencing with subatomic particles, atoms and molecules. The forces which bond atoms into molecules, molecules into chains, chains into sheets, and sheets into layers are described. Acid is defined, and the deleterious role of acid in breaking the forces which bond atoms into molecules is detailed.

The purpose of this paper is to study the mechanical response of polyurea, soda-lime glass (glass, for short), polyurea/glass/polyurea and glass/polyurea/glass sandwich structures under dynamic-loading conditions involving propagation of planar longitudinal shockwaves.

The problem of shockwave generation, propagation and interaction with material boundaries is investigated using non-equilibrium molecular dynamics. The results obtained are used to construct basic shock Hugoniot relationships associated with the propagation of shockwaves through a homogeneous material (polyurea or glass, in the present case). The fidelity of these relations is established by comparing them with their experimental counterparts, and the observed differences are rationalized in terms of the microstructural changes experienced by the shockwave-swept material. The relationships are subsequently used to predict the outcome of the interactions of shockwaves with polyurea/glass or glass/polyurea material boundaries. Molecular-level simulations are next used to directly analyze the same shockwave/material-boundary interactions.

The molecular-level simulations suggested, and the subsequent detailed microstructural analyses confirmed, the formation of topologically altered interfacial regions, i.e. polyurea/glass and glass/polyurea interphases.

To the authors’ knowledge, the present work is a first attempt to analyze, using molecular-level simulation methods, the interaction of shockwaves with material boundaries.

This paper aims to introduce a novel approach to the fabrication of photoluminescent materials by coating rare earth aluminate luminescent materials on metallic substrates and a readily manufacturable light source with robust structure in the form of photoluminescent sphere (APS).

The clean and dried stainless steel sphere was sprayed with UH 2593, a white undercoat, the luminescent coating and the weather resistance coating in chronological order.

After adhered onto the stainless steel sphere, the peaks corresponding to the N-H stretching vibrations were changed. The intensity of free N-H stretching at 3,536 cm⁻¹ dramatically decreased and the peak of hydrogen-bonded N-H stretching of PU moved to lower wavenumbers. The red shift of the infrared bands of functional groups was attributed to the strengthened hydrogen bonding. The hydrogen bonding interactions between the stainless steel substrates and the polyurethane coating endowed the APS with excellent adhesive property and also promoted the evenly distribution of the photoluminescent particles in the polymer coating matrix.

This approach can be applicable in the fabrication of the photoluminescent materials. The APS can be used as signs and guiding post in remote areas without sufficient electricity supply and in the seas and rivers with complicated hydrological conditions.

This approach has provided a method to produce tough and durable luminescent signs for remote areas and dangerous seas and explained the functional mechanism of the combined application of metallic materials and non-metallic materials.

The objective of this article is to investigate the binding of several lactones to soya protein isolate and soya protein under different conditions and, particularly, the extent of binding of the lactones γ‐9, γ‐10, δ‐10 and δ‐11, in different concentrations as well as the effect of various parameters on their binding ability.

Capillary column gas chromatography was used for the determination of lactones and the manual system was used for taking samples and for headspace analysis. Infrared spectroscopy was used for confirmation and investigation.

The percentage of binding of lactones γ‐9, γ‐10, δ‐10, δ‐11 on the soya protein is almost the same (about 33‐34 per cent). According to the Klotz equation, the bound ligand concentration was calculating as the number of moles of ligand bound per mole of protein. The results varied, but were similar. Specific experiments in water system with soya protein isolate (1 per cent) showed that the time taken for lactones γ‐10 and δ‐11 to reach equilibrium, the factors of temperature and pH affected the percentage of lactone bound.

The amount of added lactone in products containing soya protein isolate should be investigated by using panel tests to confirm the improvement of flavour.

Flavour binding of lactones can be used to provide some foods with the required flavour impression by adding lactones to a bland soy protein base.

The flavour binding of lactones, which was investigated in the present paper, has not been adequately investigated in previous scientific research and the effects of the factors that influence their binding are very important.

The high density of defects mainly attributed to the presence of silicon oxycarbides, residual C clusters, Si- and C-dangling bonds at or near the SiO₂/SiC interface degrades the performance of metal-oxide-semiconductor (MOS) devices. In the effort of further improving the quality and enhancement of the SiC oxides thickness, post-oxidation annealed by a combination of nitric acid (HNO₃) and water (H₂O) vapor technique on thermally grown wet-oxides is introduced in this work. The paper aims to discuss these issues.

A new technique of post-oxidation annealing (POA) on wet-oxidized n-type 4H-SiC in a combination of HNO₃ and H₂O vapor at various heating temperatures (70°C, 90°C and 110°C) of HNO₃ solution has been introduced in this work.

It has been revealed that the samples annealed in HNO₃ + H₂O vapour ambient by various heating temperatures of HNO₃ solution; particularly at 110°C is able to produce oxide with lower interface-state density and higher breakdown voltage as compared to wet-oxidized sample annealed in N2 ambient. The substrate properties upon oxide removal show surface roughness reduces as the heating temperature of HNO₃ solution increases, which is mainly attributed due to the significant reduction of carbon content at the SiC/SiO₂ interface by C=N passivation and CO or CO₂ out-diffusion.

Despite being as a strong oxidizing agent, vaporized HNO₃ can also be utilized as nitridation and hydrogen passivation agent in high temperature thermal oxidation ambient and these advantages were demonstrated in 4H-SiC.

This paper aims to focus on the liquefaction of soybean protein to obtain a homogeneous protein solution with a high solid/protein content but low viscosity, which may improve the bond properties and technological applicability of soybean protein adhesive.

The liquefactions of soybean protein in the presence of various amounts of sodium sulphite, urea and sodium dodecyl sulphate (SDS) are investigated, and their effects on the main properties of liquefied soybean protein and soybean protein adhesives are characterized by Fourier transform infrared spectroscopy (FT-IR), gel permeation chromatography (GPC), viscosity tracing and plywood evaluation. Meanwhile, the applicability of soybean protein adhesive composed of liquefied protein for particleboard is also investigated.

Soybean protein can be effectively liquefied to form a homogeneous protein solution with a soybean protein content of 25 per cent and viscosity as low as 772 mPa.s; the addition of sodium sulphite, urea and SDS are beneficial for the liquefaction of soybean protein and have important effects on the technological applicability and water resistance of the obtained adhesive. The optimal liquefying technology of soybean protein is obtained in the presence of 1.5 Wt.% of sodium sulphite, 5 Wt.% of urea, 1.5 Wt.% of SDS and 3 Wt.% of sodium hydroxide. The optimal soybean protein adhesive has the desired water resistance in terms of the boiling-dry-boiling aged wet bond strength, which is up to 1.08 MPa higher than the required value (0.98 MPa) for structural use according to the commercial standard JIS K6806-2003. The optimal liquefied protein has the great potential to prepare particleboard.

The protein content of liquefied soybean protein is expected to further increase from 25 to 40 Wt.% or even higher to further reduce the hot-pressing cycle or energy consumption of wood composites bonded by soybean protein adhesives.

The soybean protein adhesive composed of optimal liquefied protein has potential use in the manufacturing of structural-use plywood and has comparable applicability as a commercial urea-formaldehyde resin for the manufacturing of common particleboard.

Soybean protein adhesive is an environmentally safe bio-adhesive that does not lead to the release of toxic formaldehyde, and the renewable and abundant soybean protein can be used with higher value added by the application as wood adhesive.

A novel liquefaction approach of soybean protein is proposed, and the soybean protein adhesive based on the liquefied protein is obtained with good technological applicability and desired bond properties that extend the applications of the soybean protein adhesive from interior plywood to particleboard and exterior or structural plywood.

The purpose of this paper is to address the problems of interaction of tensile stress-waves with polyurea/fused-silica and fused-silica/polyurea interfaces, and the potential for the accompanying interfacial decohesion.

The problems are investigated using all-atom non-equilibrium molecular-dynamics methods and tools. Before these methods/tools are employed, previously determined material constitutive relations for polyurea and fused-silica are used, within an acoustic-impedance-matching procedure, to predict the outcome of the interactions of stress-waves with the material-interfaces in question. These predictions pertain solely to the stress-wave/interface interaction aspects resulting in the formation of transmitted and reflected stress- or release-waves, but do not contain any information regarding potential interfacial decohesion. Direct molecular-level simulations confirmed some of these predictions, but also provided direct evidence of the nature and the extent of interfacial decohesion. To properly model the initial state of interfacial cohesion and its degradation during stress-wave-loading, reactive forcefield potentials are utilized.

Direct molecular-level simulations of the polyurea/fused-silica interfacial regions prior to loading revealed local changes in the bonding structure, suggesting the formation of an interphase. This interphase was subsequently found to greatly affect the polyurea/fused-silica decohesion strength.

To the authors’ knowledge, the present work is the first public-domain report of the use of the non-equilibrium molecular dynamics and reactive force-field potentials to study the problem of interfacial decohesion caused by the interaction of tensile waves with material interfaces.

Looks at the major differences between food manufacture and domestic cooking. In the home, food is generally prepared immediately prior to consumption, whereas manufactured foods may need a long shelf‐life. This has great implications for the selection of ingredients and of processing and packaging techniques (and, especially, for food safety). Decisions that must be made in the selection of food ingredients and processing techniques are, in principle, much the same as those that are required in other areas of design technology. Food design and production requires a holistic approach, which can only be achieved with a good understanding of the product, the process and the packaging and how these affect one another.

The purpose of this paper is to improve binding force between the coating and the steel substrate by using chemical modification on the steel surface; at the same time, it can also increase the corrosion resistance of the coating.

The main components of the conversion film include tannic acid, sodium molybdate and silane coupling agent KH560. After the preparation was completed, the samples were tested and analyzed, including surface morphology, conversion film components, bonding force with organic resins and corrosion resistance. Finally, it drew a conclusion that the conversion film can greatly improve the bonding strength of the steel substrate and epoxy resin.

When the content of tannic acid is 4 g/L meanwhile the content of KH560 is 20 g/L, the conversion film has the strongest binding force with epoxy resin, from 2.15 Mpa of untreated steel to 4.60 Mpa, growth of 140 per cent. At the same time, the resulting conversion film also improves the corrosion resistance of the steel surface by a small margin.

A method of enhancing the bond between an epoxy coating and steel is provided. Verify the mechanism of this method.