Polymeric materials containing finely

A solution containing both the ethyltriethoxysilane monomer and its polymeric hydrolysis products was prepared by shaking a 1% (by wt.) solution of the distilled monomer in -chloronaphthalene with aqueous 0.01N HC1. The two phases were shaken intermittently for about four weeks until a finely divided precipitate—presumably polymeric material —appeared in the aqueous phase. The two phases were then separated. The organic phase was washed first with 0.1N NaHCOs, then with dis-... 

Composite rocket propeiiants. This type of propellant contains two-phase mixtures with a aystalhne oxidizer in a polymeric fuel or binder matrix. The finely dispersed powder of ammonium perchlorate suspended in a fuel is the oxidizer. The fuel is a plasticized polymeric material such as hydroxy-terminated polybutadiene cross-linked with a diisocyanate (rubber ts e) or carboxy-terminated polybutadiene (plastic type) [4]. 

A new composite material was introduced in 1987 with the discovery of a nylon-6/clay hybrid (NCH) [201]. The hybrid was prepared by the in situ thermal polymerization of s-caprolactam with 8% or less montmorillonite, the clay material containing 1-nm thick exfoliated aluminosilicate layers. It exhibited a truly nanometer-sized composite of nylon-6 and layered aluminosilicate. Figure 2.14 depicts conceptually the NCH synthesis and its fine structure. The NCH exhibited high modulus, high strength, and good gas-barrier properties. The unique and superior properties led to the commercialization of NCH. It has also created a new class of nanocomposites and worldwide interest. 

As a special form of polymeric material, fibers possess many unique properties. They are characterized by their flexibility, fineness, and a high ratio of length to width. The extreme fineness is shown by the fact that 1 kg of cotton fibers would contain about 10 individual fibers. Fibers can be utilized in a number of special applications because they are known to have the following properties. 

There is an important gronp of media materials that are not fabrics in the normally accepted sense of the word, because they are mostly not flexible, but they are made in similar ways, and serve a similar purpose, so they are included here. These are the sheets and tnbes made from bonded components fibres and granules of natural and synthetic materials. They are mainly only coarsely porous, because it is much more difficult to form very finely granular solids into useful shapes, but some fibre based materials are capable of very fine cut-off points. An important feature of this group of media is the proportion of inorganic materials that it contains, although polymeric materials are also highly featured. 

In certain chemical and biological as well in some unit operations, foaming occurs to such an extent that the process is severely impaired or even comes to a complete standstill. For example, chemical reaction systems tend to foam if a gas is formed in nascent state, because such minute gas bubbles do not coalesce to form larger ones and therefore remain in the system. Expulsion of residual monomers after emulsion polymerization often involves serious foaming problems because, in this case, very fine gas bubbles are formed in a material system which contains emulsifiers, i.e. foam producing surfactants. 

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