Dispersion Characterisation

Kissa, E. (1999) Dispersions, Characterisation, Testing and Measurement, Marcel Dekker, New York. 

Up to now we have assumed that this dispersion, characterised by the... 

Studies have been carried out using combinations of acrylic acid and isostearic acid in an attempt to produce surface modifier systems that combine effective coupling with good dispersant characterisics [13]. In this study sequential adsorption of isostearic acid and acrylic acid on to magnesium and aluminium hydroxides in the FMC cell indicated that acrylic acid will displace isostearic acid from both fillers, however, isostearic acid will adsorb onto a layer of adsorbed acrylic acid producing a hybrid layer. 

The Lennard-Jones potential is characterised by an attractive part that varies as r ° and a repulsive part that varies as These two components are drawn in Figure 4.35. The r ° variation is of course the same power-law relationship foimd for the leading term in theoretical treatments of the dispersion energy such as the Drude model. There are no... 

Diffusion and dispersion processes can be characterised by a time constant for the process, given by... 

Axial and radial dispersion or non-ideal flow in tubular reactors is usually characterised by analogy to molecular diffusion, in which the molecular diffusivity is replaced by eddy dispersion coefficients, characterising both radial and longitudinal dispersion effects. In this text, however, the discussion will be limited to that of tubular reactors with axial dispersion only. Otherwise the model equations become too complicated and beyond the capability of a simple digital simulation language. 

Table 2.7 lists techniques used to characterise carbon-blacks. Analysis of CB in rubber vulcanisates requires recovery of CB by digestion of the matrix followed by filtration, or by nonoxidative pyrolysis. Dispersion of CB within rubber products is usually assessed by the Cabot dispersion test, or by means of TEM. Kruse [46] has reviewed rubber microscopy, including the determination of the microstructure of CB in rubber compounds and vulcanisates and their qualitative and quantitative determination. Analysis of free CB features measurements of (i) particulate and aggregate size (SEM, TEM, XRD, AFM, STM) (ii) total surface area according to the BET method (ISO 4652), iodine adsorption (ISO 1304) or cetyltrimethylammonium bromide (CTAB) adsorption (ASTM D 3765) and (iii) external surface area, according to the dibutylphthalate (DBP) test (ASTM D 2414). TGA is an excellent technique for the quantification of CB in rubbers. However, it is very limited in being able to distinguish the different types of... 

PP-g-MA) silicate nanocomposites and intercalated thermoset silicate nanocomposites for flame-retardant applications were characterised by XRD and TEM [333], XRD, TEM and FTIR were also used in the study of ID CdS nanoparticle-poly(vinyl acetate) nanorod composites prepared by hydrothermal polymerisation and simultaneous sulfidation [334], The CdS nanoparticles were well dispersed in the polymer nanorods. The intercalation of polyaniline (PANI)-DDBSA (dodecylbenzene-sulfonate) into the galleries of organo-montmorillonite (MMT) was confirmed by XRD, and significantly large 4-spacing expansions (13.3-29.6A) were observed for the nanocomposites [335],... 

Presently the effective role of sulphur additive is not well explained because sometimes activation or deactivation phenomena are observed. Such a versatile behaviour is well-illustrated over noble metal-based catalysts particularly when they are dispersed on perovskite supports [111]. The catalytic performances of a prereduced Pt/LaCo03 in H2 at 450°C are illustrated in Figure 10.13a. After preactivation in H2 subsequent bulk and surface characterisation highlighted an extensive reduction of the perovskite... 

A publication summarises all the then available technical evidence related to the Seveso accident, and recommends operational criteria to ensure safety in commercial processes to produce trichlorophenol [4], All the plant scale incidents were characterised [ 1 ] by the subsequent occurrence of chloracne arising from the extremely toxic and dermatitic compound 2,3,7,8-tetrachlorodibenzodioxin (structure IX, p. S-3), formed dining the thermal runaway reaction and dispersed in the ensuing explosion. It is also extremely resistant to normal chemical decontamination procedures, and after the 1968 explosion, further cases occurred after transient contact with plant... 

Taking into account the high Mo content (5 - 7%wt) of V-Mo-ZSM-5 samples and to the conclusions of the different characterisations, we may assume that die most of molybdenum and vanadium are well dispersed on die surface of ZSM-5 in form of small oxide clusters. 

Alkaline earth oxides (AEO = MgO, CaO, and SrO) doped with 5 mol% Nd203 have been synthesised either by evaporation of nitrate solutions and decomposition, or by sol-gel method. The samples have been characterised by chemical analysis, specific surface area measurement, XRD, CO2-TPD, and FTIR spectroscopy. Their catalytic properties in propane oxidative dehydrogenation have been studied. According to detailed XRD analyses, solid solution formation took place, leading to structural defects which were agglomerated or dispersed, their relative amounts depending on the preparation procedure and on the alkaline-earth ion size match with Nd3+. Relationships between catalyst synthesis conditions, lattice defects, basicity of the solids and catalytic performance are discussed. 

In addition to natural materials, synthetic polymers might also be present in works of art. Since the end of the nineteenth century, synthetic polymers have been produced and used in the field of cultural heritage, to restore works of art [3], but also as paint binders, such as alkyd resins and acrylic water dispersions. Most synthetic polymers can be detected by GC/MS only through thermal degradation followed by GC/MS [4,5] (Chapter 12 deals with the characterisation of synthetic resins in detail). 

As with experimental work on polymer adsorption, experiments in the area of dispersion stability in the presence of polymers require detailed characterisation of the systems under study and the various controlling parameters (discussed above) to be varied in a systematic way. One should seek the answer to several questions. Is the system (thermodynamically) stable If not, what is the nature of the equilibrium state and what are the kinetics of flocculation If it is stable, under what critical conditions ( s, T, x> p etc.) can flocculation be induced ... 

This analytical approach is difficult to apply to individual pigments because physical data relating to refractive index, dispersion curves and the absorption curves in the solid state are not available. A colligative approach, based on the Kubelka-Munk analysis which characterises pigments by only two constants, an absorption and a scattering coefficient, has been applied with considerable success to the computation of the proportions of pigments in mixtures needed to match a given colour. Much of the book Colour physics for industry is devoted to this topic [37]. 

Since energy and material efficiency is dispersed over all the sectors of an economy and private households, the efficiency innovation system is characterised by ... 

The activity of chemically active AF paints usually relies on the reactivity of organometallic compounds (e.g. TBT-, Zn-, Si, Cu- acrylates and Zn-resinates) and inorganic pigments (i.e. CU2O). In spite of this, scanning electron microscopy coupled with energy dispersive X-ray detectors (SEM-EDX) has not been used extensively to characterise such reactions. Bishop and Silva... 

Angular-dispersive X-ray diffraction is used as a standard characterisation technique in the majority of solid-state laboratories. In this method, a constant-wavelength X-ray source is used. A detector sweeps a range of angles, and therefore Bragg reflections are separated by a spatial coordi-... 

Instead of considering the dispersion surface as a variable and the reciprocal lattice as invariant, it is usually easier to consider the reciprocal lattice as the variable. Then equation (8.30) determines the variation of the amplitude ratio of the reflected and transmitted components as the wavefield propagates through the crystal. The ratio R characterises a particular tie-point on the dispersion surface and if R varies the tie-point must migrate along the dispersion surface branch. This results in a change in the intensity of the transmitted and diffracted... 

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