Mechanical dispersion temperature

Reaction mixtures were prepared by mechanical dispersion of the thiol (200 mg g ) on the activated support. Water (0.5 mL g-1) was added and the mixture was carefully mixed until an homogeneous (hydrated) loose solid was obtained. This solid was left at room temperature or heated in an open vessel for the indicated time. Products were eluted from the support either with diluted hydrochloric acid (cystine, oxidized glutathione, penicylamine) or methanol (tV-acetylcystine, cystine methyl ester). The solution was decolorized by addition of activated carbon, filtered and evaporated. 

K-absorption spectrum of yttrium in YH3, which was mechanically treated in a ball planetary mill during 20 min. with angular rate of 1630 rot./min. is shown in Fig. 6 (c). This absorption spectrum, as seen from the picture, is shifted relatively to the spectrum of untreated YH3 hydride to the side of lower energies, which in accordance with the found out correlation has to testify to thermal stability of reduction of treated yttrium hydride. Actually, we determined by the method of hydrogen thermal desorption, that as a result of mechanic dispersing of this hydride its temperature of decomposition decreased more than on 300 °C (Fig. 7), i.e. the... 

The aim of this work was to investigate the effect of mechanical activation on lowering of TiH2 dissociation temperature in a nitrogen atmosphere and the mechanism of interaction of mechanically dispersed hydride with oxygen and nitrogen. 

Although the cured epoxy resins produced by the three typical curing mechanisms have different structure, the temperature dependence of the dynamic mechanical dispersion is similar as shown in Figs. 2 and 3, but Tg is different. Therefore, in order to check the relationship between the structure and Tg, q should be identical. 

This property is closely connected with the solubility parameters of polymer and dry-cleaning agent. Furthermore the dry-cleaning temperature should be outside a mechanical dispersion (transition) region of the polymer, since otherwise deformation may occur. 

As pointed out by Westlake and San Antonio (46) such factors as temperature, light, humidity, air movement, volatility of the compounds, and microorganism activity are influencing the breakdown and mechanical dispersion of residues on plant surfaces and in soils. However, within plants and animals, probably the most important single factor in pesticide breakdown and transformation is through enzymatic action. As shown in Figure 1, when a pesticide is applied to plants, animals, soils, water or air, there are many factors that may effect chemical changes, and the rates of such alterations will depend on the nature of the compound and the particular environmental conditions to which... 

Activation energies are derived from the dynamic mechanical experiments assuming that the kinetic mechanism does not change with temperature. The thus arrived at activation energy represents a lumped kinetic parameter for the reactions which have led to the point in time of the dynamics mechanical dispersion being measured. Activation energies for the first dispersion by DSA... 

Direct Emulsification. Polymer colloids called "artificial latexes" can be prepared by dispersion of bulk polymers or polymer solutions into an aqueous medium. Direct emulsification processes are reviewed by ElAasser (23). The preparation procedures involve mechanical dispersion that may be followed by removal of solvent. According to ElAasser "the efficiency of emulsification," and hence the particle size characteristics of the latex, "is determined by the efficiency of formation of fine droplets and the efficiency of stabilization of the formed droplets." Important parameters in the process include the source of energy or agitation, its intensity, and duration type and concentration of emulsifiers mode of addition of emulsifier and the two phases density ratio of the two phases temperature and the rheology of the two phases. 

At higher temperatures, the protein moiety of hpoproteins undergoes denaturation (Anton et al., 2000), which affects the structure and the surface properties. Lipids and phospholipids are liberated from their complexes with proteins so that they become better available for further reactions (e.g., extraction or oxidation), hi technological and cuhnary operations, fats and oils or their emulsions are often added to the material, they are mechanically dispersed, and hydrogen bonds between hpid and protein molecules are formed or rearranged. Other weak physical forces also play a role. The final effect depends on the particular technology employed and the composition of the food. 

For diffusion dominated processes, D is the molecular diffusivity in water of the contaminant of interest multiplied by the porosity and divided by the tortuosity (or hindrance factor, ffp) of the sediment (D = Dv,s/Hp). The Millington and Quirk model (as referenced in Palermo [1]) suggests Hp which for a cap with 40% porosity is about 1.4. The molecular diffusion coefficient in water is a function of temperature and can be estimated by the methods defined by Lyman [4]. In the presence of advection D is increased due to mechanical dispersion in the medium (typically modeled as some dispersivity, a, multiphed by the interstitial velocity, v). The dispersiv-ity is an empirical parameter but is related to the mean particle size in nearly... 

Silva et al. used low-field CPMG experiments, providing T2 distributions, for quantitative analysis of mixtures involving crude oils and water. Kashaev and Fashkiev reported relaxation studies of concentrated oil-in-water emulsions. Melnikov and co-workers studied emulsions of water in poly(ethylsiloxane) fluid, prepared by mechanical dispersion, in the presence of freon gas. At low temperatures and under pressure of freon, the... 

A detailed study on the possibility of modifying polyethylene by mechanical methods was performed by Protasov and Baramboim [32, 49]. In their investigation they used a low-density polyethylene of 35,400 and several solid monomers (methacrylamide, maleic anhydride, acenaphthylene, acrylic acid, and acrylonitrile). The mechanical dispersion was performed in a four-position eccentric vibromill with cavities and balls, diameter 6-8 mm, made of the same stainless steel. The vibration frequency was 50 Hz with an amplitude of 2-4 mm. The reaction was carried out in air at temperatures from -30 to -65" C. The formation of copolymeric products, after separation by extraction, was confirmed by many techniques (qualitative reaction... 

Maleic anhydride may be grafted to polyolefins, such as polyethylene, by mechanochemical, mechanochemical with free-radical initiators, free radical,ionic,and radiation-initiation techniques. The solid-phase mechanochemical modification studies were run by a low-temperature mechanical dispersion, extruder,die extruder,and grindingtechniques. Modification of polyethylene with <20% MA leads to crosslinking during extrusion of the polymer-anhydride blend in the extruders. This crosslinked material generally retains its form during heating to >300°C. 

Melt processing is a common and simple method, particularly useful for thermoplastic polymers. This technique consists of blending the nanoparticles with the polymer matrix in the molten state. The nanoparticles are mechanically dispersed into a polymer matrix using a high-temperature and high-shear-force mixer or compounder [192]. 

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