Ceramics organic molecules

Ceramic fibers used in composites are usually made by high-temperature methods. Carbon (graphite) fiber, for example, can be made by the thermal decomposition of fibers of polyacrylonitrile, a long-chain organic molecule also used to make the textile Orion ... 

The main message of this chapter is that the chemistry and physics of organic molecules are carryable within ceramic matrices, allowing a plethora of novel and classical applications, and providing new insight on properties of both the organic component and of the matrix itself. 

One can debate whether is an organic molecule, or just a molecular allotrope of elemental carbon in fact it is the largest molecule ever synthesized by astrophysicists [31]. The critical temperatures of ET salts seem to be stuck at about 13 K, while the fullerene salts have reached 40 K, and the ceramic superconductors are way ahead, at 150 K. 

The organic molecules from the GC are seeded in a hydrogen or helium supersonic beam and enter the vacuum chamber through a ceramic nozzle. The distance from the top of the nozzle to the surface is roughly 5 mm. In the vacuum chamber, the beam collides with ReOa or Pt surface for efficient positive ion production. The surface is always at a positive potential of 200 V against the collector electrode. The kinetic energy of the sample molecule, which is proportional to the nozzle... 

Using bifunctional organic molecules (e.g., 1,3-butadiene) and hydrosilanes, the silicon bridging units in the polymer can be varied (Scheme 15). Because of their low ceramic yield and the low thermal stability, polycarbosilanes containing longer hydrocarbon bridges are not suitable for preceramic... 

Various types of materials like metals and alloys, ceramics, different inorganic scaffolds, and low and high molar mass organic molecules are proven instrumental for the broad variety and the specific needs of bionanotechnology as... 

Laine et al. [34] have described a process where SiOj is directly reacted with ethylene glycol and an alkali to produce reactive pentacoordinate silicates, which can be used to produce silicate materials. Laine has made stable precursor polymers (>670 K), some of which are liquid crystalline, by using catechol. Agaskar [35] has prepared organolithic macromolecular materials, which are hybrids containing silicate and organic molecules (functionalized spherosilicates) and can be used as precursors for microporous ceramic (Si-C-0) materials. 

The energies of the chemical bonds and the intermolecular forces in polymers are typical of organic molecules. They are in the range that allows both chemical reactions and molecular motions at the temperatures at which polymers are used. Thus polymer properties are typically more sensitive to both temperature and time than are those of other materials, such as metals and ceramics. One consequence of the weak intermolecular forces that hold together thermoplastic polymers is that both chemical changes and molecular rearrangements can take place in time scales which are shorter than the expected lifetime and polymers may lose their desirable properties by both chemical and physical changes. 

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