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lunes, 29 de mayo de 2017

3. PLASTICS AND TEXTILES.



3. Plastics and textiles.

Keys Concepts.

1. Plastic materials.
  • Plastics consist of long chains of atoms which are mostly composed of carbon. 
  • Plastics can be classified into natural and syhnthetic plastics.
  • The process of manufacturing plastic is called polymerisation.
  • There are three types of plastic recycling processes: chemical and mechanical recycling and energy recovery. 
2. The classification by internal structure.
  • Thermoplastics are usually madre from petroleum products. The most common thermoplastics are: polyethylene terephthalate, high-density polyethylene, polyvinyl chloride, low-density polyethylene, polypropylene, moulded polystyrene, expanded polystyrene or styrofoam.
  • Thermosetting plastics are made from petroleum products. They include: polyurethane, bakelite, melamine, polyester resins.
  • Typical elastomers include rubber and neoprene. 
 3. Plastic forming techniques.
  • Various industrial techniques can be used to manufactures plastic products, such as: extrusion, calendering, vacuum forming and moulding.
  • The main techniques for using moulds are as follows: blow moulding, injection moulding and compression moulding.
4. Modification techniques.
  •  Modification techniques use tools and machines to make changes to prefabricated materials, such as sheets, bars or mouldings.
5. Textiles.
  • Both natural and synthetic fibres can be oven to make a variety of textiles.
  • Natural fibres may come from animal sources (wool, silk), plant sources (cotton, linen, esparto, bamboo) and mineral sources (gold, silver and copper fibres).
  • Synthetic fibres, such as nylon, polyester, rayon and lycra, are plastic materials.
 


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