Spherical hollow particles

Properties Spherical, hollow particles, 210 nm outer and 130 nm inner diameter, TEM image and IR spectrum available [2157]. 

C., Sanchez, C, and Charleux, B. (2008) Elaboration of monodisperse spherical hollow particles with ordered mesoporous silica shells via dual latex/ surfrtctant templating radial orientation of mesopore channels. Langmuir, 24, 13132-13137. 

Cenosphere Small, hollow, spherical ash particles formed from the combustion of liquid or solid fuels. 

CW/templated resin (TPR), 50 pm, is used for analysis of surfactants by HPLC. The templated resin in CW/TPR is a hollow, spherical DVB formed by coating DVB over a silica template. When the silica is dissolved, the hollow, spherical DVB particle formed has no micro- or mesopores [135],... 

Important examples of chemical interest include particles that move in the central held on a circular orbit (V constant) particles in a hollow sphere V = 0) spherically oscillating particles (V = kr2), and an electron on a hydrogen atom (V = 1 /47re0r). The circular orbit is used to model molecular rotation, the hollow sphere to study electrons in an atomic valence state and the three-dimensional harmonic oscillator in the analysis of vibrational spectra. Constant potential in a non-central held dehnes the motion of a free particle in a rectangular potential box, used to simulate electronic motion in solids. 

Figure 14-5 shows a photograph of a good powder produced in a small (1 m ) laboratory spray dryer. We see that it consists of spherical glassy particles, of which the largest have a diameter of about 50 pm. Many of the particles are hollow - we come back to that in a moment. The flow properties of spherical particles are expected to be good if ... 

Equations (21.61) and (21.62) are recommended for spheres or roughly spherical solid particles that form a bed with about 40 to 45 percent voids. For cylindrical particles these equations can be used with the diameter of the cylinder in Nrj and Ng,. For beds with higher void fractions or for hollow particles, such as rings, other correlations are available. ... 

For example, a novel, versatile technique for the synthesizing of uniform hollow capsules from a broad range of materials is based on a combination of colloidal templating and self-assembly processes [11.8]. Fig. 11.11 describes schematically the concept. Colloidal templates of different composition, size, and geometry (although spheroidal shape is preferred) can be employed. Materials range from spherical polymer particles to non-spherical biocolloids, all vdth diameters in the nano to micrometer range. The... 

Triblock copolymers PEO-PBO-PEO (polyethylene and -butylene oxides) in an aqueous solution of HCl were used for synthesis of silica [191] in an emulsion system containing 1,3,5-trimethylbenzene and involving tetraethyl orthosilicate as the usual cationic source. The spherical and hollow particles of silica (1-4 pm) had an ultra large mesoporous wall structure. 

A variant of the methods described above was reported by Jafelicci et al. [272] who prepared a microemulsion by addition of water or 3M nitric acid solution into a solution of NaAOT in heptane under sonication. A dilute solution of sodium silicate was added to this microemulsion and the system further sonicated. The product particles were gathered by centrifugation. The spherical silica particles (hollow under specific conditions) thus obtained had a size range of 1-10 pm. It is noteworthy that though the authors claim to have prepared particles via microemulsions, the large size of the particles does not indicate them to be a product of microemulsion-mediated synthesis in nanoreactors (see Section 5.3.1). 

The particle morphology can have important ramifications for the latex product performance. Because multi-lobed particles have a larger hydrodynamic volume than a spherical particle of equal polymer mass, such types of latexes have been used to raise the viscosity in coatings applications. Hollow particles are used in paper coatings to improve the optical properties and surface smoothness. Particles with core-shell morphologies or with domains have been developed for impact modification. In addition, various microencapsulation techniques have been employed to enclose a wide variety of materials (47, 97,239) for pharmaceutical, agricultural and cosmetic applications. 

Sukhorukov, A Kornowski, H. Mohwald, M. Giersig, A. Eychmiiller, H. Weller H, Formation of luminescent spherical coreshell particles by the consecutive adsorption of polyelectrolyte and CdTe(S) nanocrystals on latex colloids. Colloid Surface A 2000, 163, 39-44 (c) F. Caruso, Hollow capsule processing through colloidal templating and self-assembly, Chem. Eur. J. 

For the spherical particle, y>p = l and for the non-spherical particle, Shape coefficient presents the extent of difference between particle and sphere, sometimes also called as spherical coefficient. The Eqs. (7.33) and (7.34) are suitable to particles whose inner spaces are non-hollow, but not to ring-columnar hollow particles. 

Particle shape factor. The particle shape factor is a dimensionless parameter. For non-hollow particles, the shape factor is defined as the ratio of the external surface area 1S5 of a spherical particle with the same particle volume to the actual surface area Sp of the particle. This is equivalent to the ratio of the particle diameter dp to the diameter dp of a spherical particle with the same volume, that is, = Ss/Sp = ds/dp, where d = 6Vp/Sp. The shape factor indicates how much a particle differs from a spherical one. For spherical particles, 1 for non-spherical particles, is less than 1. The particle shape factor can be calculated from the volume and external surface area. The volume and external surface area for particles with... 

Spherical filler particles, usually hollow, used to reduce weight in a product without much adverse effect on mechanical properties. 

Results gained at 0.1 bar, when both the inter- and intra-particular volumes are unfilled, are similar to bulk and tapped densities (data not shown). The density calculated after filling inter-particular spaces, known as the effective particle density, differed significantly for the three different outlet temperatures (Table 14.8). The lowest density was obtained for Tout = 67 °C with 0.832 g/cm, which results in spherical carrier particles. This shows that the hollow space volume is the largest for these particles. The effective particle density rises up to 1.111 g/cm for particles dried at Tout = 102 °C, which are particles with indentations. These particles show higher mechanical stability due to its higher material per volume ratio as mentioned before. 

Lattice Dynamics of Icosahedral Alpha-Boron Under Pressure. Physical Review Letters, Vol. 78, No. 4, (January 1997), pp. 693-696, ISSN 0031-9007 Wang, Y.L. Gai, L. Xia, Y.N. (2005). Monodisperse Spherical Colloids of Pb and Their Use as Chemical Templates to Produce Hollow Particles. Advanced Materials, Vol. 17, No. 4, (February 2005), pp. 473-477, ISSN 0935-9648 Wang, Z.K. Shimizu, Y. Sasaki, T. Kawaguchi, K. Kimura, IC Koshizaki, N. (2003). Catalyst-Free Fabrication of Single Crystalline Boron Nanobelts by Laser Ablation. Chemical Physics Letters, Vol. 368, No. 5-6, Qanuary 2003), pp. 663-667, ISSN 0009-2614 Wagner, R.S. Ellis, W. C. (1964). Vapor-Liquid-Solid Mechanism of Single Crystal Growth. 

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