Aggregated particle monolith

Figure 3.69 Schematic of aggregated particle monolith preparation, (a) Initial uncoated resin slurry, (b) after graft coating the resin, (c) coated resin slurry mixed with uncoated resin, and (d) coated resin after nanobead agglomeration.

Because corrosive fluids can penetrate the refractory, such penetration usually results in disruption and even destruction of the matrix of the refractory. The matrix is the area of sintered lines that hold together bonded bricks and monolithic refractories. Usually, the matrix contains more impurities and more porosity than aggregate particles. Therefore, corrosion affects the weakest component of the refractory at a higher rate than denser or higher-purity particles. In extreme cases of matrix attack, rapid erosion of coarse refractory aggregate can occur. 

The thermal conductivity of crushed/pulverized coal is lower than that of monolithic coal. The model (above) for such two-phase systems consisting of a discontinuous phase of coal particles, and a continuous gas phase is in broad agreement with literature data and predicts that the thermal conductivity of monolithic bituminous coals is more than twice the value of their aggregates. 

The pore texture of an adsorbent is a measure of how the pore system is built. The pore texture of a monolith is a coherent macropore system with mesopores as primary pores that are highly connected or accessible through the macropores. Inorganic adsorbents often show a corpuscular structure cross-linked polymers show a network structure of inter-linked hydrocarbon chains with distinct domain sizes. Porous silicas made by agglutination or solidification of silica sols in a two-phase system are aggregates of chemically bound colloidal particles (Fig. 3.25). 

Marr and coworkers described the preparation of Pd nanoparticles-stabilised aerogels using an ionic liquid route [29]. The material was prepared by inclusion of pre-formed Pd colloids (2 nm) stabilised by imidazolium salts in a silica monolith. The material was only tested in the reaction of iodobenzene with butyl acrylate, showing good activity (TON = 2092). No aggregation of Pd particles was observed by TEM however Pd leaching, probably accounting for the activity, was detected by ICP-AES. 

Although polymers and monomers in any form such as latexes, water-soluble polymers, liquid resins, and monomers are used in cement composites such as mortar and concrete, it is very important that both cement hydration and polymer phase formation (coalescence of polymer particles and the polymerization of monomers) proceed well to yidd a monolithic matrix phase widi a network structure in which the hydrated cement phase and polymer phase interpenetrate. In the polymer-modified mortar and concrete structures, aggregates are bound by such a co-matrbc phase, resulting in the superior properties of polymer-modified mortar and conoete compared to conventional. 

Third Step. Ultimately, with water withdrawal by cement hydration, the close-packed polymer particles on the cement hydrates coalesce into continuous films or membranes, and the films or membranes bind the cement hydrates together to form a monolithic network in which the polymer phase interpenetrates throughout the cement hydrate phase. Such a structure acts as a matrix phase for latex-modified mortar and concrete, and the aggregates are bound by the matrix phase to the hardened mortar and concrete. 

When established protocols for bulk MIP syntheses were adapted for coating of flat surfaces, the MIP layers resemble the monolithic or particle aggregate structures obtained in the in situpreparation ofMIPs (cf above) [70]. However, homogeneous thin films could also be obtained using the sandwich technology, imprinting of a SPR sensor surface was demonstrated, hence MIP film thickness was less than 100 nm [72]. 

The first of these factors is filler particles aggregation. The detailed description of this effect influence on structure and properties of composites, having glassy matrix, is given in review [3]. For the considered composites this effect is important first of all for determination of filler volume fraction cp/, which is calculated by division of filler mass fraction into its density. However, filler particles in real composites exist in the form of fractal aggregates, which density can be more smaller than monolithic object of such filler. Below the example of value cp/calculation for concrete composite will be given. 

In general, the dispersion of clay particles in a polymer matrix can result in the formation of three general types of composite materials (Figure 1). Conventional composites contain clay tactoids with the layers aggregated in unintercalated face - face form. The clay tactoids are simply dispersed as a segregated phase. Intercalated clay composites are intercalation compounds of definite structure formed by the insertion of one or more molecular layers of polymer into the clay host galleries and the properties usually resemble those of the ceramic host. In contrast, exfoliated polymer-clay nanocomposites have a low clay content, a monolithic structure, a separation between layers that depends on the polymer content of the composite, and properties that reflect those of the nano-confmed polymer. 

Until the end of the last century, bulk chromatographic materials containing porous or nonporous particles were used. Monolithic materials made of synthetic or natural pol)7mers and silica-based monoliths with similar surface chemistry have also been used as additional chromatographic supports in the last 15—20 years. Due to the rapid interaction between the sample components and the surface, monolithic materials enable very fast chromatographic separation of large molecules such as proteins and nucleic adds and nanopartides such as viruses and protein aggregates [5,6]. 

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