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plastics Mario Simón Puga 3eso D - Coggle Diagram
plastics Mario Simón Puga 3eso D
1.Plastic
Plastics play a big part In our daily lives. We all know they are used for making containers and packing. But we also use plastic in many economic and industrial sectors, for example: telecomunications,constructiom,technology etc.
1.1 Origin and transformation of plastics
Depending on their origin,we can describe plastics as natural or synthetic:
Natural plastics
:directly from vegetables they are raw materials examples:cellulose or latex.
Synthetic Plastics
:are made from compounds extracted from petroleum,natural gas and carbon. The majority of plastics belong to this group.
1.2 Properties of plastics
Depend on their composition.
Streght,eslasticity,rigidity and flexibility
are characteristics of many plastics, although they vary from one type to another. However, there ara other properties that are commo0n to the majority of plastics:
mechanical: malleability, ductility, mechanical resistance.
acoustic
:acoutic insulation.
electrical
:electrical insulation.
thermal
:thermal insulation.
other properties**:low density impermeability.
1.3 Ecological properties
Chemical recycling
We apply chemical processes to make new materials from the original components.
Mechanical recycling
We make new products from plastic granules.
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Classification of plastics
2.1 Thermoplastics We manufacture thermoplastics from compounds acquired from petroleum. They're made up of weakly formed molecular chains.
2.2
Thermostable
These plastics are made from compounds derived from petroleum. They are formed by strongly-lnked chains. Whem heated make soft.
2.3
Elastomers
Made by vulcanisation: mixing sulphur and rubber, and heating to 160 degrees.
They are hard, resistant and vey elastic-streching easily under force.
3.
formation techniques
When we manufacturate platic objects in indstry, the plastic is avalible in three different forms: powder, granules and resins.
3.1
Extrusion
. This technique has four stages: 1. We put thermoplatic, in granular form, into a previously heated cylinder. 2.We apply preassure by means of a lare, rotating screw, wich forces the melted material out, though a nozzle. 3. We cool the shaped material slowly in a refrigerated water bath until it's solid. 4. Finally we collect the pieces of plastic through a feeder system.
3.2
Lamination
Thermoplastic prduced by the extrusion method is passed througha series of hot cylinders to produce sheets of varying thickness. With this technique, we can produce different finishes.
3.3
Vacuum forming
We use sheet with a large surface for this technique.
3.4
Moulding
There are principal techniues: injectionblow moulding and compression. Injection moulding 1. We inject melted thermoplastic into a mould.
When the material has cooled and solidified, we extract it from the mould.
Blow moulding 1. We put a tubular-shaped piece of plastic into a hollow mould which has the same shape as the object that we wan to make. 2. We close the mould and blow presurised air into it, so that the plastics adheres to the sides of the mould and takes its shape. 3. When the object is cold, we remove it from the mould.
