Miscibility temperature studies

The system H2S-CH4-H20 is an example of a ternary system forming a continuous range of mixed hydrates of Structure I. For this system Noaker and Katz22 studied the H2S/CH4 ratio of the gas in equilibrium with aqueous liquid and hydrate. From the variation of this ratio with total pressure at constant temperature it follows that complete miscibility must occur in the solid phase. 

In the fourth section the influence of comonomeric units on the polymorphic behavior of some polymers is described. In particular it is shown that comonomeric units can produce changes in the solid-solid transition temperatures as well as variations of the crystalline forms, which can be obtained for a given crystallization procedure. In the same section, some recent studies, showing that the polymorphic behavior of some polymers can be altered in particular miscible blends, are also reviewed. 

With diblock copolymers, similar behavior is also observed. One component is enriched at the surface and depending on miscibility and composition a surface-induced ordered lamellar structure normal to the surface may be formed. Recent investigations include poly (urethanes) [111], poly(methoxy poly (ethyleneglycol) methacrylate)/PS [112] and PS/PMMA [113, 114]. In particular the last case has been extensively studied by various techniques including XPS, SIMS, NR and optical interferometry. PS is enriched at the surface depending on blockcopolymer composition and temperature. A well ordered lamellar structure normal to the surface is found under favourable conditions. Another example is shown in Fig. 6 where the enrichment of poly(paramethylstyrene), PMS(H), in a thin film of a di-... 

Vapor quenching provides a method of bridging the miscibility gap which exists in many alloy systems, and makes a range of novel alloys available for study. Such films, of course, would not be ideal for catalytic studies. They could not be used at high temperatures, and indeed the heat of reaction might be sufficient to induce a transformation to a more stable structure. In addition, characterization by X-ray diffraction would be difficult, even for the crystalline films, because of line broadening by the small crystallites. Nevertheless, alloy films which are metastable above room temperature can be prepared, and their high surface area would... 

In general, the miscibility between two polymers can be predicted by thermal characterization of the blends [36], One of the most simple and effective ways to predict miscibility between two polymers is to consider the behavior of the glass transition temperature in the blend systems, which is known as the Tg method. In miscible blend systems, only a single 7 g intermediate between two components appears in the amorphous state. Therefore, we studied the change of... 

---