Cooling natural fibers

Most stop-leak products consist of small pieces of natural fibers (vegetable or inorganic). Before considering the use of any particular stop-leak preparation, its suitability and also compatibility with the coolant in use should be known. The solids in stop-leak compounds may result in plugging or excessive deposit formation in the cooling system. 

The forming method has it that isotactic polypropylene is formed as a board on which one or more parallel layers of fibers are applied. Additionally, on one side, the ends of fibers must reach out over the edge of the board to be caught and puUed. Next, the second polypropylene board is applied. The boards are heated to 175-285°C at a constant or increased pressure, and then the set is cooled down. Below 150°C, the fibers are moved to the distance up to few millimeters at 0.01-0.1 m/s. Having obtained the desired shape, the product is cooled down to the ambient temperature [3]. The technique presented in the cited patent description ensures high content of p form in the polypropylene composite reinforced with natural fiber. 

Recently, new compounding methods have been investigated to produce long, natural fiber-reinforced thermoplastic pellets and improve composite mechanical properties [31, 32]. For example, pellets have been formed by melt impregnation of continuous natural fiber yarns by pultrusion followed by cooling and chopping. Another method involves commingling of continuous forms of natural and synthetic fibers that are then heated, consolidated, and chopped. 

The properties of silk includes, (i) versatile and very comfortable, (ii) absorbs moisture, (iii) cool to wear in the summer yet warm to wear in winter, (iv) easily dyed, (v) strongest natural fiber and is lustrous, and (vi) poor resistance to sunlight exposure [57]. 

Fig. 2.18 illustrates the nature of the intensity profiles in pure polyetheretherke-tone (PEEK) and carbon fiber reinforced PEEK composites in the transmission and reflection modes, respectively. The quenched amorphous and slowly cooled crystalline components from PEEK can be separated. The three prominent diffraction peaks from the crystalline components in Fig. 2.18(a) correspond to the three uniform rings which can be detected in X-ray photographs. In contrast, no clearly measurable signal is identified from the PEEK amorphous phase independent of the carbon fiber content. 

The fill material in natural draft cooling towers is frequently asbestos cement. Erosion of this fill material may result in the discharge of asbestos in cooling water blowdown. In a testing program for detection of asbestos fibers in the waters of 18 cooling systems, seven of the 18 sites... 

Berries and leaves of certain plants have been used for centuries to provide the colors necessary to make wool, cotton, flax, silk, and other fabric fibers with an attractive shade differing from the natural colors of the materials. These colors were usually boiled with the formed fabric or yarn to impart color. Additional processes such as cooling the solution and/or the addition of lime, carbonate (chalk), or vinegar was found useful to set the color onto the fabric and impart some degree of fastness. 

Better yields of carbon black are obtained by improved separation of the combustion function from the carbon-forming function, as is accomplished in the newer furnace black processes. This approach enables gas oil (high boiling point liquid petroleum fractions) or natural gas to be used to produce carbon black. The cooling function from 1,400°C to about 200°C is accomplished by direct water sprays. The product is removed from the gas stream via a combination of cyclone collectors and glass or Teflon fiber bag filters. One tonne of furnace black is obtained from 5,300 to 7, OOOm (1 atm 15.6°C) of natural gas, or 1,400-2,800 L of gas oil corresponding to 50-70% yields. Oil-based furnace black now supplies about 90% of the current carbon black market, although the special features of the product from small-scale processors still contribute some product [4]. 

From most solvents Ss crystallizes as orthorhombic a-Ss. Monoclinic pSg is stable above 96 °C and is usually obtained by cooling liquid sulfur slowly below the triple-point temperature of 115 °C. At 25 crystals of pSg convert to polycrystalline a-Ss in less than 1 h but are stable for several weeks at temperatures below -20 C [27]. y-S is metastable at all temperatmes and occasionally crystallizes by chance, for example from ethanolic solutions of ammonium polysulfide [28], by decomposition of copper ethybcanthate [29] or in the preparation of bis(dialkylthiophosphoryl)disulfane [30]. Smpris-ingly, y-Ss occurs also naturally as the minerd rosickyite. Fmthermore, 7-8 is a component of stretched plastic sulfur which is obtained by quenching liquid sulfur from 350 C to 20 °C (in cold water) and stretching the fibers obtained in the direction of their axes. According to an X-ray diffraction study, this fibrous sulfur consists of helical polymeric sulfur chains (S[Pg.7]

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