Liquid pitch melts

Three major breakthroughs in process technology have recently been made. These processes facilitate the growth from a liquid phase. They inciude the formation of (1) InP, InAs and GaAs whiskers [18] from other organic soivents by a soiution-iiquid-soiid phase transformation, (2) short carbon fibers from liquid pitch melts by centrifuging [19], and (3) silver nanowires by a novel self-assembly process [71]. Micro- and nanopillars (or micro-and nanocolumns) are a new class of short inorganic fibers. They are... 

Liquid pitch and bitumen, one part of each. Throw it on and melt and stir. 

Air Water Olive oil Glycerin 10 5 10 3 1(T 1 1 Gas Liquid Liquid Thick liquid Polymeric melts Pitch Glass O O o o o toffee-like stiff rigid... 

A relatively new class of high-performance carbon fibers is melt-spun from mesophase pitch, a discotic nematic liquid crystalline material. This variety of carbon fibers is unique in that it can develop extended graphitic crystallinity during carbonization, in contrast to current carbon fibers produced from PAN. 

The melt-spinning process used to convert mesophase pitch into fiber form is similar to that employed for many thermoplastic polymers. Normally, an extruder melts the pitch and pumps it into the spin pack. Typically, the molten pitch is filtered before being extruded through a multi-holed spinnerette. The pitch is subjected to high extensional and shear stresses as it approaches and flows through the spinnerette capillaries. The associated torques tend to orient the liquid crystalline pitch in a regular transverse pattern. Upon emerging from the... 

To date, there has been relatively little work reported on the mesophase pitch rheology which takes into account its liquid crystalline nature. However, several researchers have performed classical viscometric studies on pitch samples during and after their transformation to mesophase. While these results provide no information pertaining to the development of texture in mesophase pitch-based carbon fibers, this information is of empirical value in comparing pitches and predicting their spinnability, as well as predicting the approximate temperature at which an untested pitch may be melt-spun. 

Pliny gives a description of a process a little more systematic for the recovery of tar from the torch tree. The wood is chopped into small billets, placed in a furnace which is heated by fires lighted on every side. The first liquid that exudes flows like water into a reservoir made for its reception. In Syria, this substance is known as cedrium, and it possesses such remarkable power that in Egypt the bodies of the dead after being steeped in it are preserved from corruption. The liquid that follows is of thicker consistency and constitutes pitch properly so called. This is apparently a somewhat elaborated method of melting out... 

There are one or two exceptions to this rule, however, such as glass and pitch. These substances remain soft for a considerable interval of temperature, becoming less and less viscous as the temperature rises, until they ultimately hquefy. This property is peculiar to so-called amorphous, i.e. non-crystalline, bodies. We shall exclude bodies of this kind from consideration, and also hquid crystals and crystalhne fiuids, substances which appear to combine the characteristic properties of the sofid and of the hquid states. They have the fixed configuration of the molecules in space peculiar to sohds, as well as the mobihty of liquids. The transition from an anisotropic crystal to a perfectly isotropic fluid always takes place at one definite temperature. The softening of crystals in the neighbourhood of the melting point is not an exception to this rule, since these softened crystals are still anisotropic. 

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