Microspheres, hollow

Glass beads (solid), microspheres (hollow) and glass flake... 

Microspheres (hollow) Reduced weight improved stiffness and impact resistance... 

Decreased density is possible through use of fillers such as wood flour (or fibre), hollow glass microspheres, hollow polymer microspheres [22] (e.g., Expancel ) or hollow spheres from fly ash. Eow-density thermoplastic composites are useful for products that must float. 

Figure 9.7 (a) Absorption of Congo red with time by new MnOj microspherical hollow hierarchical nanostructures ... 

Syntactic foam contains an orderly arrangement of hollow sphere fillers. They are usually glass microspheres approximately 100 microns (4 mils) in diameter, provide strong, impervious supports for otherwise weak, irregular voids. As a result, syntactic foam has attracted considerable attention both as a convenient and relatively lightweight buoyancy material and as a porous solid with excellent shock attenuating characteristics. The latter characteristic is achieved... 

Results of uniaxial strain static and gas gun compression tests on syntactic foam have been conducted. The foam was buoyant and composed of hollow glass microspheres (average diameter 100 microns) embedded in an epoxy plastic. Static testing consists of compressing a 0.25 cm x 2.5 cm dia. wafer between carefully aligned 2.5 cm dia. steel pistons. Lateral expansion of the wafer is... 

DL Wilcox, M Berg, T Bemat, D Kellerman, JK Cochran, eds. Hollow and Solid Spheres and Microspheres Science and Technology Associated with Their Eabrication and Application. Vol 372. Pitsburgh Materials Research Society Proceedings, 1995. 

Initially glass microspheres were used in the 1970s to overcome severe lost circulation problems in the Ural Mountains. The technology has been used in other sites [1189]. Hollow glass beads reduce the density of a drilling fluid and can be used for underbalanced drilling [1199-1201]. Field applications have been reported [73]. 

Materials formed by acid-base reactions between calcium aluminate compounds and phosphate-containing solutions yield high-strength, low-permeability, C02-resistant cements when cured in hydrothermal environments. The addition of hollow aluminosilicate microspheres to the uncured matrix constituents yields slurries with densities as low as approximately 1200 kg/m, which cure to produce materials with properties meeting the criteria for well cementing. These formulations also exhibit low rates of carbona-tion. The cementing formulations are pumpable at temperatures up to 150° C. 

H. Ma. Study on the stability of low density cement with hollow microsphere. Drilling Fluid Completion Fluid, 10(l) 61-65,76, January 1993. 

Lu W, Gao W, Wang S (2008) One-pot synthesis of Ag/ZnO self-assembled 3d hollow microspheres with enhanced photocatalytic performance. J Phys Chem C 112 16792-16800... 

Pan JH, Zhang X, Du Alan J, Sun DD, Leckie JO (2009) Self-etching reconstruction of hierarchically mesoporous F-Ti02 hollow microspherical photocatalyst for concurrent membrane water purifications. J Am Chem Soc 130 11256-11257... 

By changing the ultrasound power, changes in the mesoporosity of ZnO nanoparticles (average pore sizes from 2.5 to 14.3 nm) have been observed. In addition to the changes in mesoporosity, changes in the morphology have also been noted [13]. Recently, Jia et al. [14] have used sonochemistry and prepared hollow ZnO microspheres with diameter 500 nm assembled by nanoparticles using carbon spheres as template. Such specific structure of hollow spheres has applications in nanoelectronics, nanophotonics and nanomedicine. 

Bourlinos AB, Karakassides MA, Petridis D (2001) Synthesis and characterisation of hollow clay microspheres through a resin template approach. Chem Commun 16 1518-1519... 

Fowler, C.E., Khushalani, D. and Mann, S. (2001) Facile synthesis of hollow silica microspheres. Journal of Materials Chemistry, 11, 1968—1971. 

Muthusamy, E., Walsh, D. and Mann, S. (2002) Morphosynthesis of organoclay microspheres with spongelike or hollow interiors. Advanced Materials, 14, 969—972. 

The silica microspheres provide some diversity but not enough for many complex discrimination tasks. To introduce more sensor variety, hollow polymeric microspheres have been fabricated8. The preparation of these hollow microspheres involves coating silica microspheres by living radical polymerization, using the surface as the initiation site. Once the polymer layer forms on the silica microbead surface, the silica core is removed by chemical etching. These hollow spheres can be derivatized with the dye of interest. The main advantage of these polymer microspheres is the variety of monomers that can be employed in their fabrication to produce sensors with many different surface functionalities and polymer compositions. 

Mandal T. K., Fleming M. S., Walt D. R., Production of hollow polymeric microspheres by surface-confined living radical polymerization on silica templates, Chem. Mater. 2000 12 3481-7. 

Schmitt, M.L., J.E. Shelby and M.M. Hall, Preparation of hollow glass microspheres from sol-gel derived glass for application in hydrogen gas storage. /. Non-Crystalline Solids, 352, 626-631,2006. 

PCA [Precipitation with a compressed anti-solvent] A process for making a solid with unusual morphology by spraying a solution of it into a supercritical fluid. The process resembles spray drying into a supercritical fluid. Used for making microspheres, microporous fibers, and hollow microporous fibers. 

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