2. Student 1
1st Sourcing of raw materials
Raw materials can come from: minerals, plants, or animals.
They are extracted from nature.
Then they are modified so they obtain plastic properties.
Examples:
-Plant origin
Rubbers and gums are made from latex, a liquid extracted from tropical
trees.
Rayon and cellophane are made from cotton and wood cellulose.
Varnishes are made from the oil of oily seeds.
4. -Animal origin
For making shellac it is used the resin secretion from an insect called lac.
Galalith and lanital are made from one protein called casein found in milk.
lac bug galalith
5. -Mineral origin
The basic substances, called monomers are extracted from fossil
fuels.
2nd Synthesis of monomers
In this process, the basic substances are extracted from raw materials throw
chemical reactions.
Then they are transformed into plastic substances.
Is carried out in petrochemical industries.
6. Shaping and finishing
This process is when the plastic substance are manufactured and
transformed into products.
Thermocompression
For making thermosetting plastic products.
The process:
The plastic is pass trough a hot mold then is compresd and when it has the
mold shape and has cold down it is pulled out.
Extrusion molding
The plastic is introduced in a heat pipe then the hot screw moves the plastic
foreward.
Then the melted plastic is shaped.
Finally is cooled down and cut in measured pieces.
7. Blow molding
The plastic is form with a different method.
Then is introduced in a closed mold with pressurized air which makes the plastic to the
walls.
Finally when its called down is removed.
Thermocompression Extrusion molding Blow molding
8. Student 2
3rd Synthesis of basic polymers
Plastics are made up of different components.
The quantities vary according to the kind of plastic we want to obtain.
Then, chemical ractions (polymerization,polycondensation and polyaddition occur).
This chemical processes change the properties and the shape of the components.
9. 4th Incorporation of additives
Chemical products that give several properties to the polymers
Dyes: change the color of the polymers
Plastizers: make the surface of the material brighter
Antistatic agents: take dust away by reducing the static electricity charge
10. Additives
Fireproof agents: make the polymers resist fire
UV stabilizers: make the polymers resist UV radiation and atmospheric phenomena
Fillers, reinforcements, and lubricants: made better mechanical processes and make easier
the manufacturing process
Mold release agents: made easier the extraction of the polymer from a mold
Antioxidants: prevent the oxygen to cause chemical reactions
-UV stabilizers action
12. Shaping and finishing
Injection molding: Is the process in which a polymer is injected ,in a liquid state,
inside a mold
Foam molding: process that concerns some gases and its usually used to create
softpolymers
13. Shaping and finishing
Vacuum forming: you place a plastic sheet in a mold with some channels, it is heated so that a
vacuum which will compress the sheet so that it take the shape
Calandering: in this process we have to pass the polymer between the hot rollers and it will be
compressed by them
14. Student 3
Physical Properties of Plastics
electrical conductivity:
- is an electrical phenomenon.
- where a material contains particles with electric charge.
-Has a high capacity of insulation
15. Thermal conductivity:
- is the property of a material to conduct heat.
-In SI units, thermal conductivity is measured in watts per meter kelvin.
Density:
-It was discovered by Arquimedes.
-High thermal and chemical resistance.
-Low density polymer.
16. Thermal Expansion
-When an object is heated or cooled, its length change by an amount
proportional to the original length and the change in temperature.
Melting point
It depends of what the plastic its made of :
-If it is made of LDPE its melting point will be at the temperature of 150 Cº.
-And it is made of HLPE its melting point will be 135 Cº.
17. Mechanical Properties of Plastics
Types of stress
-Traction: two opposites forces that pull the plastic to the sides.
-Compression: Two opposites forces that pull the plastic to the centre.
-Shearing: its the deformation of a plastic in two different directions
.
-Torsion: Bend a plastic without breaking it.
-Plasticity: it’s a capacity of plastics to undergo a deformation in a
compressed form.
-Elasticity: Its how much flexibility have an object.
-Malleability: When you can deform a plastic althought its cold.
18. -Ductility: Is an ability of a hard material.
-Resistance: It’s the ability os supporting an stress without breaking.
-Hardness: resistance without scratching.
-Weldability: Ability of joining with other materials when the material heats.
Chemical properties
-Permeability(NO) Ability of passing throught a solid without changing its
structure.
-Solubility: (NO) : ability of mixing with homogeneous mixtures.
-Combustibility (YES) : ability of burning.
19. Biological Properties
-Recyclability (YES) : ability of changing into an useful material
-Toxicity (YES) : When materials are affected by toxic products.
-Biodegradability (NO) : it’s the effect that causes the descomposition of the
environment
20. Student 4
Plastic materials classification
Thermosetting: -properties: fragile, difficulty of processing.
-characteristics: Light weight, high flexibility.
-applications: handle of frying pan, car body.
Thermoplastics: -properties: deform with heat, recycleable.
-characteristics: very fragile, very rigid.
-applications: bottles, polyethylene.
Elastomers: -properties: can’t melt, insoluble.
-characteristics: low density, resistance.
-applications: silicones, rubbers……
