High solid solutions

Poly(vinylpyrrolidone-co-acrylamide) (PVP-Am) forms readily as a high molecular weight polymer in aqueous solutions in the presence of free radical initiators. The preparation and characterization of these copolymers has been reported, jhe copolymers prepared for this study were prepared by homogeneous polymerization as 9.1-20% (w/w) solutions. When the polymerization was complete, usually in 8-24 hours, these high solids solutions were rigid and gel-like in appearance. The linearity of the copolymer was evident on dilution, for they dissolved to form gel free, filtrable viscous aqueous solutions. 

In the course of this work, we discovered that the process surprisingly allows polymerizations to be carried out at substan tially lower temperatures and/or in much shorter reaction times than those previously possible using common organlc soluble initiators. This has tremendous advantages, especially in bulk or high solids solution polymerizations, in reducing problems associated with heat dissipation. Shorter reaction times also have their obvious economic advantages. 

Release systems based on this condensation cure chemistry are commonly sold as two-part packages. One (A) is a high-solids solution of the silanol-terminated high viscosity polymer (commonly called a gum) plus the methylhy-drogen crosslinker. The second part (B) is a solution of the tin soap catalyst. Further dilution of the A and B mixture is then done with more solvent to achieve an approximate 5-10% solids content the bath is then adequately coat-able by techniques such as reverse roll, rotogravure, metering rod, or doctor blade. 

A simple latex mastic for applying ceramic tiles and wood flooring can be made by adding a high solids solution ( > 80% solids) of an appropriate tackifying resin to an SBR latex with sufficient agitation to disperse the resin in the latex. Fillers may also be used in such a formulation. Such a mastic would then be applied to the floor or wall by trowel. The tile to be bonded is applied immediately with pressure before a skin forms on the mastic. 

Additional advances in high solids solution paint systems are achieved through further formulation optimisation which include ... 

For adhesion to ferrous metals a two part bonding agent should be used. A primer coat is applied to the shot blasted metal followed by the tie or cover coat. For maximum adhesion, a liberal coat of high solids solution (35 % solids) based on the polychloroprene compound dissolved in toluene should be applied over the cover coat. 

There is a number of very pleasing and instructive relationships between adsorption from a binary solution at the solid-solution interface and that at the solution-vapor and the solid-vapor interfaces. The subject is sufficiently specialized, however, that the reader is referred to the general references and, in particular, to Ref. 153. Finally, some studies on the effect of high pressure (up to several thousand atmospheres) on binary adsorption isotherms have been reported [154]. Quite appreciable effects were found, indicating that significant partial molal volume changes may occur on adsorption. 

Alkaline-Earth Titanates. Some physical properties of representative alkaline-earth titanates ate Hsted in Table 15. The most important apphcations of these titanates are in the manufacture of electronic components (109). The most important member of the class is barium titanate, BaTi03, which owes its significance to its exceptionally high dielectric constant and its piezoelectric and ferroelectric properties. Further, because barium titanate easily forms solid solutions with strontium titanate, lead titanate, zirconium oxide, and tin oxide, the electrical properties can be modified within wide limits. Barium titanate may be made by, eg, cocalcination of barium carbonate and titanium dioxide at ca 1200°C. With the exception of Ba2Ti04, barium orthotitanate, titanates do not contain discrete TiO ions but ate mixed oxides. Ba2Ti04 has the P-K SO stmcture in which distorted tetrahedral TiO ions occur. 

The dominant mechanism of purification for column ciystallization of sohd-solution systems is reciystallization. The rate of mass transfer resulting from reciystallization is related to the concentrations of the solid phase and free hquid which are in intimate contac t. A model based on height-of-transfer-unit (HTU) concepts representing the composition profQe in the purification sec tion for the high-melting component of a binaiy solid-solution system has been reported by Powers et al. (in Zief and Wilcox, op. cit., p. 363) for total-reflux operation. Typical data for the purification of a solid-solution system, azobenzene-stilbene, are shown in Fig. 22-10. The column ciystallizer was operated... 

The addition of MgO leads to the formation of a naiTow range of solid solutions at high temperamre, which decompose to precipitate inclusions of tetragonal Zr02 dispersed in cubic zirconia. The material, which functions as a solid electrolyte, has the added advantage that the inclusions stop the propagation of any cracks which may arise from rapid temperature change. 

The equation for the rate of oxidation of the transition metals at high temperatures, which form a solid solution of oxygen before the oxide appears at the surface has die same form as that derived for die carburizing of die metal, and... 

Strong materials either have a high intrinsic strength, /, (like diamond), or they rely on the superposition of. solid solution strengthening obstacles fo and work-hardening f i, (like high-tensile steels). But before we can use this information, one problem... 

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