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:no_entry:PLASTICS:no_entry: - Coggle Diagram
:no_entry:PLASTICS:no_entry:
1.1- Origin and transformation of plastics
Natural plastics
are obtained directly from raw vegetable matenals
Synthetics plastics
are made from compounds extracted from petroleum, natural gas and carbon The maionty of plastics belong to this group
1.2 Properties of plastics
electrical
thermal
acustic
other propeties
mechanical
1.3 ecologial properties
mechanical recycling
3-agglutination
4-extrusion
2-floating
5-pelletising
1-separation and crushing
chermical recycling
2 CLASSIFICATION OS PLASTICS
2.1- thermoplastics
We manufacture thermoplastics from compounds acquired from petroleum. They' re made up of weakly formed molecular chains. When we heat them, they become soft, which allows them to be formed into different shapes
2.2-thermostable plastics
These plastics are made from compounds dertved from petroleum. They are formed by strongly-linked chams runmng in different directions.
2.3-elastomers
Made by vulcanisationi mixing sulphur and rubber, and heating to 160ºC.They are hard, resistant and very elastic — stretching easily under force.
3 FORMATION TECHNIQUES
3.1- extrusion
1- we put thermoplastics, in granular form, into a previously heated cylinder
2- we apply pressure by means of a large, roating screw, which forces the melted material out, through a nozzle
3- we cool the shaped material slowy in a refrigerated water bath until it's solid
finally, we collect the pieces of plastics through a feeder system
3.2-lamination
Thermoplastic produced by the extrusion method ls passed through a
senes of hot cylinders to produce sheets of varying thickness
With this technique, we can produce different finishes, for example,
glossy, matt or textured.
This depends on the outer coating applied by the
final cylinder.
3.3. Vacuum forming
3- We extract the air below the sheet so that the plastic ts pulled against
the instde walls of the shaped mould, and the desired form ts created
1- We put thermoplasttc into a mould
4- We leave the mould to cool, then remove the obiect
2- We then use a heater to heat the mould and soften the plasuc.
3.4. Moulding
injection
1- We tniect melted thermoplastic into a mould
2- When the material has cooled and solidified, we extract tt from the
mould
blow moduling
2- We close the mould and blow pressurised air into it, so that the
plastic adheres to the sides of the mould and takes its shape.
3- When the object is cold, we remove it from the mould.
1- We put a tubular-shaped piece of plastic into a hollow mould which
has the same shape as the oblect that we want to make
compression
1- We put thermostable plastic, which can be in granular form,
into the base of a cavity mould
4- We extract the oblect when the plastic has cooled and solidified
3- The plastic adapts to the shape of the cavity between the two parts of
the mould
2- The outer part of the cavity mould, shaped the same, is closed to compress the matenal inside We then heat it and it becomes soft and mafleabie
4 SHAPING AND FINISHING TECHINES
Cutting
fretsaw
to cut soft, low density plastics
jig saw
to cut very large sheets of plastics, and rihid plastics in general
steel bit
to cou sheets less than 1 min in thickness
power press
to cut flat sheets of low density plastics
scissors
to cut saoft, thin flexible sheets
hot metal thread trimmer
to cut sheets of soft thermoplastics
cutter
to cut sheets of diferent thickness
Perforing
Drill bit: tool that makes holes in plastics
Trimming and filing
a file has a rough surface - used to finish the surfaces and edges of hard materials
5- JOINING PLASTICS
5.1-Temporary joints
mechanical fasteners
standard crew
used to fasten two objects
double ended screw
each end oh the screw can be inserted into one of a pair of objects
nut and bolt
used to fasten two objects together
5.2 Permanent joints
Adhesives: joining two surfaces mpermanently
main types:
-resins with two components
-acrylic cement
-comtact adhesives
Soldering: joining thermoplastics using heat and pressure