Plastic Profile

Plastics are polymeric materials, a material built up from long repeating chains of molecules. Polymers such as rubber occur naturally, but it was not until the development of synthetic polymers around year of 1910 that the polymers tailored to the needs of the engineer first started to appear.During the Second World War, plastics such as nylon and polyethylene were used as a replacement material for other materials in short supply.

The mechanical properties of plastics tend to be inferior to most metals. Fibre reinforced plastics are extensively used where the mechanical properties of the base plastic material are not sufficient. However, because of their relatively low weight, the ability to colour the plastics when manufacturing and the ability to mould complex shapes relatively easily, plastics are extensively used for product casings and other applications where mechanical strength is not at a premium.

Plastics are not cheap materials. The cost of raw plastic materials is typically higher than steel but less than aluminium. However, because processing costs over large production runs are lower, the use of plastics can result in significantly cheaper products. For applications requiring strength, the plastics can be reinforced by fibres, usually glass, which give the material added strength. There are two main families of plastics, thermoset plastics and thermo plastics.

Thermo plastics become soft when heated. They can be easily moulded and remoulded without significant degrading. Thermo plastics consist of long molecular chains with no regular structure or very little regular structure.

thermo plastics available:

---Polyethylene ---Polystyrene
---Polycarbonate ---Nylon
---Acrylic ---Acetal

Thermoset plastics are rigid plastics, resistant to higher temperatures than thermoplastics. Once set, a thermoset plastics cannot be remoulded.

thermoset plastics available:

---Expoxies---Polyester

There are about 50 different groups of plastics, with hundreds of different varieties. All types of plastic are recyclable. To make sorting and thus recycling easier, the American Society of Plastics Industry developed a standard marking code to help consumers identify and sort the main types of plastic. These types and their most common uses are:

Polyethylene terephthalate - Fizzy drink bottles and oven-ready meal trays.

High-density polyethylene - Bottles for milk and washing-up liquids.

Polyvinyl chloride - Food trays, cling film, bottles for squash, mineral water and shampoo.

Low density polyethylene - Carrier bags and bin liners.

Polypropylene - Margarine tubs and microwaveable meal trays.

Polystyrene - Foam meat or fish trays, hamburger boxes and egg cartons, vending cups, plastic cutlery, protective packaging for electronic goods and toys.

Any other plastics that do not fall into any of the above categories. - An example is melamine, which is often used in plastic plates and cups.