Cooling thermoplastics

Solid raw materials have to be transferred into a fluid or plastic state, which is, nearly always, attained by heating (in exceptional cases by solution). In the fluid state the material is shaped, after which the resulting shape is fixed by cooling (thermoplasts), or by a chemical reaction (curing of thermosets, vulcanisation of rubbers). 

Thermoplasts, after being combined with energy carriers, are processed on hot rollers into a plastic material. The subsequent shaping is achieved by means of hydraulic mold presses and cutting machines. Depending on the binder type, the resulting powder kernels are cured (thermoset material), cooled (thermoplast), or dried by the removal of solvents (gelatin). 

All polymers can be divided into two major groups thermoplastics and thermosets) based on their thermal processing behavior. Thermoplastics soften and flow when heated. Upon cooling, thermoplastic polymers harden and assume the shape of the mold. Examples of commercial thermoplastics include polystyrene, polyolefins (e.g. polyethylene and polypropylene), nylon, poly(vinyl) chloride (PVC), and poly (ethylene) terephthalate (PET). Thermoplastics make up 80% of the plastic produced today and these polymers are linear or branched in their structure. 

A method of rapidly cooling thermoplastic parts when they are removed from the mold, usually by submerging the parts in water. 

Quenching A process of shock cooling thermoplastic materials from the molten state, usually done experimentally with thin films of crystal-forming polymers in order to minimize the crystalline content and to study the nearly amorphous material. 

In polymer chemistry, the term plastic refers to any polymer that can be molded when hot and that retains its shape when cooled. Thermoplastics are polymers which, when melted, become sufficiently fluid that they can be molded into shapes that are retained when they are cooled. Thermosetting plastics, or thermosets, can be molded when they are... 

Linear and branched polymers are often soluble in solvents such as chloroform, benzene, toluene, DMSO, and THF. In addition, many linear and branched polymers can be melted to form highly viscous liquids. In polymer chemistry, the term plastic refers to any polymer that can be molded when hot and retains its shape when cooled. Thermoplastics are polymers that can be melted and become sufficiently fluid that they can be molded into shapes that are retained when they are cooled. Thermosetting plastics, or thermosets, can be molded when they are first prepared, but once they cool, they harden irreversibly and cannot be remelted. Because of these very different physical characteristics, thermoplastics and thermosets must be processed differently and are used in very different applications. 

Shrinkage of a plastic as it cools (thermoplastic) or polymerizes (thermoset) is a fact of life, often specified as parts per thousand or, for example, as six thousandths of an inch per inch of mold shrinkage. Such mold shrinkage is reasonably easy to compensate for by making the cavity proportionately larger in all dimensions. 

Thermopiastics consist of macromoiecuies physically linked by either linear or branched bonds. Uniike eiastomers and thermosets, they are not crosslinked. They are rigid at iow temperatures, but when heated they soften to a plastic state in which they can be shaped relatively easily. This process is reversible, i.e., when cooled, thermoplastics resolidify. Between their hard, energy elastic state and their melt state lies their entropy elastic range [1]. 

The technology used to manufacture ICS yams evolved over several years and different prototype machines. While the concept of the final version may have been part of the original vision, it is evident that several alternative approaches were also tried. The key feature of the earlier proposals was to embed staple fibers into an extruded, but not fuUy cooled, thermoplastic... 

Thermoplastics are solids or semisolids that become liquified at elevated temperatures. Hazardous-waste materials can be mixed with hot thermoplastic hquids and solidified in the cooled thermoplastic matrix, which is rigid but deformable. The thermoplastic material most used for this purpose is asphalt bitumen. Other thermoplastics, such as paraffin and polyethylene, have also been used to immobilize hazardous wastes. 

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