Microscopic investigations dispersion

SEM studies of composites were carried out using a JEOL JSM-T300 scanning electron microscope. Energy dispersive X-ray (EDX) analysis was performed by energy dispersive device LINK 860-500 attached to the SEM unit. JEOL-JEM-200 transmission electron microscope was used for TEM investigations. 

In HRTEM, very thin samples can be treated as weak-phase objects (WPOs) whereby the image intensity can be correlated with the projected electrostatic potential of crystals, leading to atomic structural information. Furthermore, the detection of electron-stimulated XRE in the electron microscope (energy dispersive X-ray spectroscopy, or EDX, discussed in the following sections) permits simultaneous determination of chemical compositions of catalysts to the sub-nanometer level. Both the surface and bulk structures of catalysts can be investigated. 

Compositional Characterization. The composition of the bulk samples was not determined since the components to these refractories were not considered sufficiently volatile to distort the nominal stoichiometry. Micro-analysis of the materials was performed in an effort to determine the homogeneity of the product crystals. These EDAX (Energy Dispersive X-ray Analysis) studies were performed by use of a Phillips model 505 scanning electron microscope. Microscopic investigation of the macrostructure of the ceramic were also performed using this instrument. 

The main focus of the measurement programme was the rheological measurements with the high-pressure capillary viscometer. In addition, a number of measurements were performed with the aim of permitting statements about the dispersion state (pyrolysis, microscopic investigations) and determining (conductivity measurements). 

Hydrolysis of the beaten Cladophora was carried out in boiling 4N HCl for 44 hr mass recovery was 22%. In another preparation, an unbeaten sample from a different strain of Cladophora glomerata, which was harvested from a different location at a different time of year, was subjected to the same hydrolysis conditions mass yield was 12%. In the latter case, electron microscopic investigation (21) of sonicated and dispersed... 

Fig. 5.8 Fracture resistance of filler-reinforced SBR/BR blends as a function of the macro dispersion index DI DI was determined by a light-microscopic investigation and is a measure for the number of filler agglomerates being larger than 3-5 pm.

The separated colloid-rich phase can either appear in a low dispersed state or in higher dispersed states. In the first case macroscopic or microscopic investigation allows one to distinguish between crystallisation when obviously crystalline individuals (see Fig. 1) are formed and coacervation, when amorphous liquid drops are formed (see p. 235,... 

In the cases which are called flocculation, the separated colloid-rich phase is present in a higher dispersed state and here it frequently costs a great deal of trouble or it is no longer possible by microscopic investigation of the floccules to determine to which category the separated phase belongs. 

To fully assess the properties of suspension concentrates, three main types of measurements are required. Firstly some information is needed on the structure of the solid/solution interface at a molecular level. This requires investigation of the double layer properties (for systems stabilised by ionic surfactants and polyelectrolytes), adsorption of the surfactant or polymer as well as the extension of the layer from the interface (adsorbed layer thickness). Secondly, one needs to obtain information on the state of dispersion on standing, such as its flocculation and crystal growth. This requires measurement of the particle size distribution as a function of time and microscopic investigation of flocculation. The spontaneity of dispersion on dilution, i.e. reversibility of flocculation needs also to be assessed. Finally, information on the bulk properties of the suspension on standing is required, which can be obtained using rheological measurements. The methods that may be applied for suspension concentrates are described briefly below. 

During electron microscope investigation Fig. 17.1 it was founded that the fine material stmcture of springs produced by SSTMT method was tmiform with characteristic increased density of dislocations, subbotmdaries, disperse equally distributed carbide particles. Average ferrite matrix substmcture elements constituted 20. .. 40 nm at the dispersion of up to 100 nm. 

The rheological properties, especially the dynamic-mechanical properties, can be very useful in predicting the dispersion of the nanofiller. In rubber nanocomposites, the observed Payne effect can be correlated with microscopic investigation, and often both these characteristics are consistent. 

The samples for the measurements of physical-mechanical parameters represented different types of Roman cement mortars, such as casts, renders with high and low ratios of cementiaggregate, and finally a blend of Roman cement with Kme. The latter, a rather common procedure to produce soft renders at their times, can be easily identified with the naked eye by its white lumps of badly dispersed lime and was confirmed through microscopic investigations. 

Polymer nanocomposites are prospective new materials. Nevertheless, their properties are still not well understood. The chapter by Heinz, Patnaik, Pandey, and Farmer ( Modeling of Polymer Matrix Nanocomposites ) demonstrates the application of modem computational methods for investigating dispersion of various nanofiHers in polymer matrices under the action of microscopic forces. In addition, an attempt is made to calculate the thermal conductivity in a model system of nanotubes in polymer matrix. 

TEM is used to investigate the phase morphology of polymer blends and the dispersion of fillers. See Electron Microscope. 

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