Silicates organo compounds

To take advantage of both modified layered silicate and the substantial presence of phosphorus, the combined use of phosphorus-modified silicates and phosphorus compounds may represent an innovative solution to achieve high levels of flame retardancy. Phosphonium-modified layered silicates in epoxy resins were associated with organo-phosphorus FRs by Schartel et al.59 Ion exchange of Na-montmorillonite was carried out using tetraphenyl phosphonium bromide. Triphenyl phosphate and a reactive phosphorus compound were used as FR incorporated in the epoxy resin. 

SiCl4 is the starting material for the synthesis of organo-functional silicon compounds and is utilized in the manufacture of highly dispersed SiO, (pyrogenic silicic acid) and for the silization of metallic objects. Tetrafluorosilane (SiF4) see Section 1.7.1.3.2. Hexafluorosilicic acid (H2SiF6) see Sections 1.7.1.3.2 and 1.7.1.3.3. 

The coal sodium originally present as chloride and organo-metallic compounds is rapidly volatilized in the pulverized coal flame <23). Subsequently the volatile species are partly dissolved in the surface layer of flame heated silicate particles and partly sulphated in the flue gas (8). The formation of sodium sulphate can proceed via two routes ... 

The mineral matter in coal consists chiefly of silicate, sulphide, carbonate species, and chlorides and organo-metallic compounds associated with the fuel substance (1,2). The silicate mineral particles vitrify partially or completely, in the pulverized coal flame ( 3), and thus the silicate ash fraction of the initial deposit consists of particles of variable amounts of a glassy phase and crystalline species ( ). 

Many of the non-silica compositions showed problems with the stability and quality of the structure. Efforts to address these issues have been on going and quite successful in some cases such as all-alumina compositions (see below). Silica-based materials remain dominant as the most versatile and best quality molecular sieves (structure and stability) available by a facile synthesis. These attributes, especially the convenient synthesis made mesoporous silicate attractive for post-synthesis functionalization with other elements as well as organic moieties with active groups/ccnters. Recently the compositional diversity has been extended further to include both silica and organic moieties within the framework. The new class is referred to as periodic mesoporous organosilicas (PMOs). The synthesis involves surfactant-assisted assembly by hydrolysis of organo-silicon compounds. Additional discussion of the PMOs is presented below. 

Virtually all treatments in commercial use are chosen to chemically bond an organic species to the filler surface, thus improving compatibility with organic polymers. The most common functionalities used for this are acids or acid precursors, such as anhydrides (for basic or amphoteric fillers) and alkoxy-silanes (for fillers with metal hydroxyls present, especially siliceous fillers). Organo-titanates and related compounds are also proposed for nse with a wide variety of fillers. 

In this section, PCL-based nanocomposites have been synthesized by in-situ intercalative polymerization of e-CL in the presence of various organo-modified (Cloisite 25A, Cloisite 30B) or non-modified (Cloisite Na layered silicates . As previously mentioned, this synthetic approach involves dispersion of the aluminosilicate platelets in the liquid monomer followed by polymerization (in bulk or in solution) by either thermal or catalytic activation using organometallic compounds (aluminium or tin alkoxides for instance). Depending on the nature of the filler and/or the activation mode, different composite morphologies can be obtained. 

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