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.