摘要:

The structure of amorphous alloys has been studied by using various techniques, such as x-ray, neutron, and electron diffraction experiments. X-ray diffraction is the most conventional of all the techniques and is based on EXAFS (extended x-ray absorption fine structure) [1-3] and AXS (anomalous x-ray scattering) [4-5] experiments, which are used for the investigation of the local environment around a species of atom. Recently, x-ray diffraction has been applied to the structural analysis of some quasicrystals [5,7]. It is, of course, hard to determine the local structure of a noncrystalline material only from ordinary x-ray diffraction experiments. However, the role of x-ray diffraction in structural analysis is still important from the viewpoint that this supplies a relatively convenient method, and the appropriate selection of a Sample makes it possible to extract the dominant atomic correlation in the material. In the present study, a conventional -2 diffractometer was used with a monochrometor in the diffracted beam. First, the theoretical background is discussed, the data analysis procedure is given in detail, and error estimation in the data analysis is presented last.

ISSN:0360-2559    

DOI:10.1080/03602559508012189

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

Polyethylene (PE) and polypropylene (PP) films were grafted with an acrylic acid/2 hydroxyethyl methacrylate (AAc/HEMA) mixture under nitrogen atmosphere using a60Co gamma source. Some parameters affecting the grafting percentage of this binary mixture have been studied. These parameters include effect of: inhibitor concentration, type of inhibitor, monomer concentrations, monomer composition, and type of solvent. The grafted films were characterized by water uptake, scanning electron microscopy (SEM), contact angle 8, differential scanning calorimetry (DSC), and spectroscopic analysis. 2-Hydroxyethyl methacrylate was found to be more reactive than acrylic acid towards graft copolymerization.

ISSN:0360-2559    

DOI:10.1080/03602559508012190

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

In the ionic xanthate method of grafting, the increase of sodium hydroxide concentration and liquor ratio increased the grafting parameters up to a limit. The limit varied from one monomer to another. The positive values of the standard degree of concentration of sodium hydroxide indicate that the graft polymerization reaction has happened. The extent of decrease in the grafting parameters with the increase of the liquor ratio may be due to the increase of the termination reactions as a result of increasing the number of HOH molecules and the consequent chain transfer reactions to solvent. Grafting parameters also increased with the increase of the concentration of monomers up to a limit. The reactivity of these monomers is in the order: methyl methacrylate > ethyl acrylate > allyl chloride > acrylonitrile > methyl acrylate > allyl alcohol, being dependent on both the radical stabilization and the strength of the electron acceptance of the monomers. The activation energy of the overall polymerization reaction (i.e., grafting and homopolymer) decreased with the increase of the crude grafting yield, and the reverse relation was achieved with the true grafting yield (i.e., grafting reaction only). This difference may be attributed to the difference in the conformation of the polymer chains to graft polymerize on the active sites of the cellulose chains.

ISSN:0360-2559    

DOI:10.1080/03602559508012191

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

An analytical study is performed to examine the effects of a magnetic field on free convection flow when: (i) plate is moving impulsively with uniform velocityU; (ii) suction velocity normal to the plate is constant; (iii) fluid is subjected to a constant heat source of absorption type; (iv) magnetic lines of forces are assumed to be fixed relative to the porous plate; (v) magnetic field makes an angle α normal to the porous plate. The expressions for the velocity field and skin friction are obtained by the Laplace transform technique. The influences of the various parameters on flow field and skin friction are extensively discussed.

ISSN:0360-2559    

DOI:10.1080/03602559508012192

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

Polyethylene (PE), a general-purpose thermoplastic, finds wide-ranging applications in many areas such as packaging films, electrical insulations, housewares, pipes and tubings, etc. [I]. For certain applications such as the insulation and sheathing of power cables used for off-shore mining, flame retardancy is an essential service requirement. Some of the other applications for flame-proofed polyolefins include components for TV sets and waste pipes [2]. Flame retardancy has long been achieved by the use of additives based on compounds of elements such as phosphorus, halogen, nitrogen, antimony, aluminum, etc. [3-5]. However, the use of such additives should not affect the processability of the formulations adversely. This can be ensured by studying the processability characteristics of the flame-retardant modified polymer on a rheometer under conditions of temperature and shear rate simulating those of the process to be followed. The Brabender Plasticorder has been shown to be ideal equipment in this respect.

ISSN:0360-2559    

DOI:10.1080/03602559508012193

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

The effects of allylmethacrylate on the copolymer of allylmethac-rylate and methylmethacrylate have been studied by varying the allylmethacrylate content in the feed from 5% to 30% by volume. It has been found that above 15% allylmethacrylate content in the feed, the molecular weight between crosslinks increases, reducing the crosslink density and thereby causing a reduction in the mechanical properties. Up to 10% allylmethacrylate, the strength remains high and the modulus also increases; and up to 15% the modulus increases but the strength value drops down. There is a sharp drop in both strength and modulus after 15%. Thus the addition of 10% allylmethacrylate has been found to give the optimum mechanical properties.

ISSN:0360-2559    

DOI:10.1080/03602559508012194

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

Leather surface has been modified with UV-cured film of urethane triacrylate in the presence of variable concentrations of mono-functional monomers such asN-vinyl pyrrolidone (NVP) and ethyl hexyl acrylate (EHA). Incorporation of small amounts of plasticizer into the formulation has substantially enhanced both tensile strength and elongation of the coated leather. Addition of a difunctional monomer such as tripropyl glycol diacrylate (TPGDA) to the system has increased the tensile property further.

ISSN:0360-2559    

DOI:10.1080/03602559508012195

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

Blends of diglycidyl ether of bisphenol-A epoxy resin and adipic acid, ethylene glycol, diethylene glycol polyester copolymer have been studied regarding viscosity behavior. Both the rheological measurements carried out on the molten mixtures over a large interval of shear rates and the intrinsic viscosity of the blend solutions pointed to an immiscibility at temperatures ranging from 30° to 90°C. The rheological parameters evaluated on the flow of the mixtures against temperature and the shear rate led to the conclusion that the tested blends have a non-Newtonian rheological behavior of the pseudoplastic type.

ISSN:0360-2559    

DOI:10.1080/03602559508012196

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

An integral solution for Herschel-Bulkley fluid flow development in a straight channel is presented. The analysis not only accounts for the loss of energy due to viscous dissipation in the boundary layer, but evaluates wall-shear stress as integrals involving axial velocity distribution, which is obtained by cross-sectional integration of the equation of momentum. Results are compared with other integral solutions for several values of Herschel-Bulkley number and flow behavior index.

ISSN:0360-2559    

DOI:10.1080/03602559508012197

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

A prototype of a new disk-type viscous pump with radial pumping grooves on its stator (as previously reported) has been successfully fabricated and experimentally tested for rotor speeds of 600, 900, 1200, 1500, and 1800 rpm, at a nominal rotor-stator gap of 133 μm. The test results of each speed reveal gradual increase in the working fluid temperature which makes its pressure-flow rate relationships no longer linear in practice. This can be the main practical problem in operating such a pump, and for this reason, a few methods of comparison between the test results and the analytical predictions have been proposed. By minimizing the time taken for data collection, the test results obtained agree very well with the analytical predictions for all the speeds tested. This experimental study has also demonstrated that this new disk-type viscous pump is practically feasible.

ISSN:0360-2559    

DOI:10.1080/03602559508012198

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor