Cooling melt blowing

Since the air carrying molten polymer particles from the melt generator to the substrate is a poor heat insulator, the transported particles cool down quickly. Figure 3.28 illustrates the catastrophic heat energy loss by PE melt particles sprayed in atmosphere by a melt-blowing device [52]. 

Immediately below the die, a large amount of ambient air is drawn into the hot air stream containing the microfibers. This air cools the hot gas and solidifies the fibers. The distance between the die and the forming belt is relatively short and can readily be adjusted from a few centimeters to 50 cm in a properly designed melt blowing line. This is an important process parameter. 

Based on these results, a new injection device for foam extrusion is designed with emphasis on the complete dissolution of blowing agent into the polymer melt and the cooling of the polymer melt/blowing agent solution. 

No external heat source is required. In all types of steelmaking that employ pig iron, which melts at temperatures well below low carbon steel, the heat balance between exothermic oxidation of elements, such as C, Si, and Mn, and the cooling provided by scrap or sometimes other endothermic coolants, such as iron ore, are critical issues. The numerical factors are well understood and are routinely contained in computer programs used by operators. If the balance is such that the temperature after blowing is too high, refractory consumption is increased significantly. 

Blow Molding. Blow mol ding is a multistep fabrication process for manufacturing hoUow symmetrical objects. The granules are melted and a parison is obtained by extmsion or by injection mol ding. The parison is then enclosed by the mold, and pressure or vacuum is appHed to force the material to assume the contour of the mold. After sufficient cooling, the object is ejected. 

Production molds are usually made from steel for pressure molding that requires heating or cooling channels, strength to resist the forming forces, and/or wear resistance to withstand the wear due to plastic melts, particularly that which has glass and other abrasive fillers. However most blow molds are cast or machined from aluminum, beryllium copper, zinc, or Kirksite due to their fast heat transfer characteristics. But where they require extra performances steel is used. 

The nature of these processes requires the supply of clean compressed air to blow the hot melt located within the blow mold. Other gases can be used, such as carbon dioxide, to speed up cooling of the blown melt in the mold. The gas usually requires at least a... 

The crystallinity in PET soft drink bottles is about 25%. Because a more crystalline state is normal for PET, the amorphous content is increased intentionally by copolymerization and rapid cooling for the molten PET from the melt to a temperature below the glass transition temperature. Companies which perform high-speed blow molding of PET prefer PET resins made with small amounts of glycol and diacid comonomers. 

Prepare the copper oxide-lead chromate as follows Spread a thin layer of coarse copper oxide over a small iron plate, heat from above with a blow pipe until the glow is as bright as possible and sprinkle with a thin layer of finely powdered lead chromate. The chromate melts at once and spreads over the copper oxide forming a firmly adherent layer and causing the strips of copper oxide to stick together a little. Now turn the cake over and treat the under side in the same way. When the mass has cooled break it up gently in a mortar and remove powder and unduly large pieces with a sieve. 

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