High-strength microsphere

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. 

Amos SE, et al. High strength, low density glass microspheres for extruded and injection molded plastics. Automotives TPOs, conference proceedings. Society of Plastics Engineers 2007. 

Zeeospheres, Fine particle size, high-strength ceramic microspheres, Zeelan Industries, Inc., Subs, of 3M... 

The combination of high strength and electrical conductivity can be combined to produce highly novel phenomena. For example, in 1999 Lieber and co-workers prepared "nanotube nanotweezers". Two nanotubes were attached to independent electrodes and positioned near each other. When a voltage bias was placed across the two, the two nanotubes reversibly bent toward each other, fully mimicking the motions of a tweezer. These electrically activated tweezers can grab and manipulate polystyrene microspheres or silicon carbide nanoclusters. This early work could presage the development of true nanomachines that could perform unprecedented operations on a near-atomic distance scale. 

Z-Light Spheres Low-density hollow ceramic microspheres, 3M Zesospheres Fine size, high-strength ceramic rnicrospheres, 3M Zelec Antistatic agents, DuPont Zelux Polycarbonate shapes, Westlake Zenite LCP Liquid crystal polymers, DuPont... 

In order to obtain in practice the theoretical highest apparent density of the syntactic foam, the mixture has to be molded at the pressure at which the microspheres pack the closest. Several methods (mold vibration, high molding pressures, etc.) have been recommended as ways of obtaining a syntactic foam density close or equal to y by helping the microspheres pack more closely and thus approach the foam s maximum strength. It should be remembered that ideal packing is never actually achieved and there is always some disorder 80). 

The polymer employed to prepare microspheres must be characterized in terms of molecular weight and purity,however this topic is beyond the scope of this article. Characterization of the materials may have implications for the formation of the microspheres. The viscosity and film-forming properties of the polymers used should be known. Viscosity can affect the tendency to form microspheres, their size, and even their shape. Burgess and coworkers have shown that albumin-acacia coacervates do not form microcapsules under certain conditions of pH and ionic strength, if the viscosity of the coacervate phase is too high. Burgess and Carless developed a method to predict the optimum conditions for complex coacer-vation based on the charge carried by the two polymers involved. 

Due to the extremely low density of the microspheres, the resultant syntactic foam is low in density. It also has high physical strength, especially compressive strength. Other features of the syntactic foam include isotropic physical properties and low water absorption. The latter has led to application in deep sea submersible vehicles. Recently applications have expanded to other areas, including aircraft. 

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