Barium Systems

Mention has already been made of epoxide stabilisers. They are of two classes and are rarely used alone. The first class are the epoxidised oils, which are commonly employed in conjunction with the cadmium-barium systems. The second class are the conventional bis-phenol A epoxide resins (see Chapter 22). Although rarely employed alone, used in conjunction with a trace of zinc octoate (2 parts resin, 0.1 part octoate) compounds may be produced with very good heat stability. 

Phase Diagrams, Intermetallic Phases and Compounds 7.3.3.1.5. Barium Systems. 

Figure 15 illustrates the effect of a 45-minute dwell time on two plastisols containing 75 p.h.r. of DOP with different stabilizer systems. The upper example is a liquid cadmium-barium system and the lower a thiotin-dibutyltin maleate system. The organotin system is obviously the more effective. The leading yellow zone, which is followed by a dark zone, may indicate two different breakdown mechanisms. 

Barrer and Mainwaring (20) report the use of metakaolin as the aluminosilicate raw material for reaction with the hydroxides of K and Ba as well as the binary base systems Ba-K and Ba-TMA to form zeolites. Zeolite phases previously synthesized in the analogous hydrous aluminosilicate gel systems were crystallized with KOH, including phillipsite-, chabazite-, K-F-, and L-type structures. The barium system yielded two unidentified zeolite phases (Ba-T and Ba-N) and a species Ba-G,L with a structural resemblance to Linde zeolite L. Ba-G,L was reported previously by Barrer and Marshall (21) as Ba-G. Similar phases were formed in the Ba-K system and in the TMA-Ba system where, in addition, erionite-type phases were formed. The L-type structures are said to represent aluminous analogs of the zeolite L previously reported (22). 

In the triphenyhnethanides, the metal is coordinatively and electronically saturated by the encompassing crown ether that occupies an equatorial plane around the metal, as well as by the axially located HMPA donors. This favorable cation coordination enviromnent is well established in alkaline earth metal chemistry. The hgands are free to adopt the most conformationally stable orientation, and steric demands force the rings away from planarity and in both the strontimn and barium systems the rings display the familiar propeller geometry, comparable to that seen for related alkali systems. 

Synthetic phases apparently related to the phillipsite group occur in the K and K-Na systems. One such phase, designated Zeolite W by Linde (7), appears to be analogous to Barrers K-M (I). Barrer also has reported a Ba-M phase in the barium system which is described as harmotome-like (3). Related phases which occur in systems other than pure Na will not be discussed further here. 

In the ternary alkaline earth octylsulphate-decanol-water system, the extension of the lamellar liquid crystalline phase towards the water comer increases in the order Mg " > Ca + > Ba (28 moles 0 per mole surfactant ion for magnesium against 18 moles for the calcium system and not quantified for the barium system). On the other hand, the minimum amount of water necessary to form the lamellar liquid crystalline phase in the calcium and magnesium systems is approximately the same, 8 moles per mole surfactant ion [4],... 

The solubility of oxide in the chloride melt increases by increasing the basicity of the system from the calcium system to the barium system. 

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