Inorganic volume fraction

Relative (a) tensile modulus and (b) yield stress of polypropylene nanocomposites plotted as a function of inorganic volume fraction of filler. The dotted lines serve as guides. (Reproduced from Mittal, V., Eur. Polym. 43, 3727, 2007. With permission from Elsevier.)... 

E and E correspond to the elastic moduli of composite and matrix, respectively represents the shape factor, which is dependent on filler geometry and loading direction q)f is the inorganic volume fraction 11 is given by the expression... 

Physical Properties. Physical properties of importance include particle size, density, volume fraction of intraparticle and extraparticle voids when packed into adsorbent beds, strength, attrition resistance, and dustiness. These properties can be varied intentionally to tailor adsorbents to specific apphcations (See Adsorption liquid separation Aluminum compounds, aluminum oxide (alumna) Carbon, activated carbon Ion exchange Molecular sieves and Silicon compounds, synthetic inorganic silicates). 

Sohd rocket propellants represent a very special case of a particulate composite ia which inorganic propellant particles, about 75% by volume, are bound ia an organic matrix such as polyurethane. An essential requirement is that the composite be uniform to promote a steady burning reaction (1). Further examples of particulate composites are those with metal matrices and iaclude cermets, which consist of ceramic particles ia a metal matrix, and dispersion hardened alloys, ia which the particles may be metal oxides or intermetallic compounds with smaller diameters and lower volume fractions than those ia cermets (1). The general nature of particulate reinforcement is such that the resulting composite material is macroscopicaHy isotropic. 

Although the terms nanocomposite and hybrid are often used to define similar materials, we will use the classification indicated by Vilatelaand Eder [1], Nanocomposites are multiphase materials, in which one phase is dispersed in a second phase, resulting in a combination of the individual properties of the component materials. The volume fraction of the nanocarbon is typically less than a few percent. Nanocarbon hybrids are instead formed by both components with similar volume fractions. The inorganic compound (such as semiconductor nanoparticles) is deposited onto the surface of the... 

Nanocarbon hybrids have recently been introduced as a new class of multifunctional composite materials [18]. In these hybrids, the nanocarbon is coated by a polymer or by the inorganic material in the form of a thin amorphous, polycrystalline or single-crystalline film. The close proximity and similar size domain/volume fraction of the two phases within a nanocarbon hybrid introduce the interface as a powerful new parameter. Interfacial processes such as charge and energy transfer create synergistic effects that improve the properties of the individual components and even create new properties [19]. We recently developed a simple dry wrapping method to fabricate a special class of nanocarbon hybrid, W03 /carbon nanotube (CNT) coaxial cable structure (Fig. 17.2), in which W03 layers act as an electrochromic component while aligned... 

Crosslinked polymers are widely used as dental materials (1-31. Perhaps the most challenging application is in the restoration of teeth (4). The monomers must be non-toxic and capable of rapid polymerization in the presence of oxygen and water. The products should have properties comparable to tooth enamel and dentin and a service life of more than a few years. In current restorative materials such properties are sought using so-called "dental composites" which contain high volume fractions of particulate Inorganic fillers (5-71. However in the present article attention is concentrated on one commonly used crosslinked polymeric component, and on the way in which some of its properties are influenced by low volume fractions of fillers. 

Hence, the addition of inorganic impermeable nanoplatelets improves the barrier properties of polymers. This is attributed mostly to the lengthening of the diffusion path of the permeating gas molecules due to the increase of the tortuosity. Increasing the aspect ratio of the platelets and their volume fraction improves these... 

In Figure 1 a conparison is made between the volume fraction of inorganic salt in the water solution and the surface tension divided by the Beerbower correction factor, divided by the cube root of the molar volume. Using this data, in addition to the data found in Table I, we are able to make reasonable approximations for the Cohesive Energy Density parameters associated with various concentrations of inorganic salt solutions. 

The openness (e.g., volume fraction) and the nature of the pores affect the permeability and permselectivity of porous inorganic membranes. Porosity data can be derived from mercury porosimetry information. Membranes with higher porosities possess more open porous structure, thus generally leading to higher permeation rates for the same pore size. Porous inorganic membranes, particularly ceramic membranes, have a porosity... 

The type of mesostructure obtained depends strongly on the surfactant to inorganic ratio. In fact, there is a close correlation between the surfactant to solvent ratio in the phase diagram of a surfactant and the surfactant to inorganic ratio in the mesostructured materials obtained. Alberius et al. demonstrated this correlation by the so-called general predictive synthesis approach. They used the phase diagrams of the water-surfactant system to guide the synthesis of mesoporous silica and titania films. There was a very close correlation between the values of the volume fraction of the surfactant over which different phases are obtained in the water-surfactant system and in the silica-surfactant and titania-surfactant systems. 

Figure 20.4. Predicted Young s modulus E of a composite containing platelet-shaped inorganic fillers of E=100000 MPa in a matrix material with E=2000 MPa, in the ideal limit where the platelets are dispersed perfectly and aligned parallel to the direction of mechanical deformation. The curve labels denote the volume fraction of the filler.

For scratch resistance improvement of organic surfaces also nano-composites are of interest. In a composite nano-scale boehmite or y-aluminia particles of about 15 nm diameter have been used as catalysts for epoxy groups linked to hydrolyseable and condensable silanes. Epoxy polymerization preferably takes place around the nanoparticles and additionally =Si-0-Al= bonds are formed between the silanes and the alumina surface [486]. It seems that the nano-particles, only 5% in volume fraction, are flexibly suspended in an inorganic-organic network. Such systems can be produced as transparent coatings and cured at relatively low temperatures of 90 to 120°C to high performance scratch resistant layers. 

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