2. STUDENT 1:
*Sourcing of raw materials:
Raw materials can be of:
-Vegetal origin from tropical tres line, cotton, wood…
-Animal origin wool, fur and leather
-Mineral origin plastics are composed of pretoleum, carbón and fossil fuel gold,
plastics, iron…
3. *Synthesis of monomers:
Monomers basic substances.
Consists of the extraction of monomers from raw materials chemical reactions
petrochemical industries ethylene, propylene
4. *Methods of shaping and fishing plastics:
-Thermocompression thermosetting plastic products
5. -Extrusion molding →pipes,bars and laminated profiles.
Plastic → chute into a heat pipe → the worm screw makes the plastic move forward
→ plastic goes to an opening which shapes it → cooling chamber → cool and
hardened → measure.
-Blow molding → containers for liquids.
It is put in a mold → pressurized air → plastic sticks to the walls → when it is cooled
and hardened → opens and the piece is removed.
6. STUDENT 2:
*Synthesis of basic polymers:
Plastics are prepared by mixing components
When they are mixed together subjected to chemical processes (polymerization,
polycondensation, polyaddition) modifies their properties, making new materials in
grains, resins, flakes…
7. *Additives:
These are chemical products added in the precise proportions to give the polymer
properties like thermal and electrical conductivity, resistance to fire, rigidity, flexibility, etc.
-Dyes or pigments: give it color.
plasticity
-Plasticizers: improves
the shine on the surface.
-Antistatic agents: Reduce static electric charge in order to the dust and dirty not
to stick
-Fireproof or fire-retardant agents: delay formation of flames.
UV radiations
-UV stabilizers: Protect it decomposition
atmospheric phenomena
8. -Fillers, reinforcements, and lubricants: improve and facilitate
-Mold release agents: make the piece come out of the mold easily.
-Antioxidants: prevent reactions with oxygen.
mechanical properties
manufacturing process
9. *Methods of shaping and finishing plastics:
-Injection molding is used to make objects with complex shapes.
-Foam molding is used to make packaging, pillows, and sponges.
-Vacuum forming is used to make glasses, packaging, and boxes.
-Commercial shapes is used for commercial use, plastics are presented in bars.
Injection molding Vacuum
molding
Foam Calendaring
Molding
11. *Physical properties:
-Electrical conductivity: let current flow through it.
plastic low conductivity
A. Heeger, A. McDiarmid, H. Shirakawa Nobel prize in 2000 developed polymers that
conduct electricity
12. -Thermal conductivity: let hit pass through it.
Plastics low thermal conductivity
-Density: amount of material mass per unit of volume plastic is low
low weight
13. -Expansion: relative variation in the dimensions of a material because of temperature.
SOLID LIQUID LIQUID SOLID
Plastics High coefficient of expansion
Reinforced plastics low coefficient of expansión
-Melting Point: temperature when a solid becomes a liquid
200ºC later
-Fusibility: amount of heat needed to melt materials
14. *Mechanical properties:
traction
compression
-Types of stresses: bending
shearing
torsión
-Traction: a material is subjucted by two opposing forces that pull on it.
It gets broken if it
is very strong
15. -Compression: two opposite forces that push on it.
it can be broken
-Bending: subjected by two forces trying to bend it.
-Shearing: subjected by two opposite forces acting in different pints close to each other and try
to cut the material.
17. Elasticity: is the ability of a material to deform when it goes under the force of a stress
Limit point yield point
Plasticity: ability of a material to remain deformed by a stress when it is removed.
18. -Malleability: ability of a material to be permanently deformed under compression.
-Ductility: ability of a material to be permanently deformed under traction.
Used to make bars
and wires
19. -Resistance: ability of a material to undergo stress without breaking.
-Hardness: ability of a material to resist being scratched or punctured.
-Weldeability: ability of a material to join solidly with another when heated.
Weldability Hardness
20. *Chemical properties:
-Permeability: ability of a material to let fluids to flow throw them.
Normally plastics are impermeable
-Solubility: ability of a material to mix homogeneously with
another substance solvent
-Combustibility: ability of a material to burn.
Plastics burn easily but is polluting
21. *Biological properties:
-Recyclability: ability to produce from a used product a new one.
Recycle separate different materials
-Toxicity: ability of a material to produce
negative effects on
living organisms.
-Biodegradability: ability of
a material to decompose.
22. STUDENT 4:
*Plastic materials are classified in three groups:
-Thermosetting : They are petroquemical materials and they can´t deform easily , it can only
deform with heat and if it is at 170 °C.
23. *Thermosetting they are divided in five groups:
-Phenolic resins: They are hard, insoluble, resistant to very high temperatures.
You can use it to buttons, switches, handles, and kitchen utensil handles.
24. -Ureic resins impermeable to liquids.
You can use it for electrical accessories, handles, door and drawer knobs,bottle caps, plates,
cups, and pans.
-Melamine resins impermeable to liquids and elastic.
You can used it for household furniture.
Polyester resins they are good electrical and thermal insulators ,also mixed with a
catalyst. Mixed with fiberglass, they are used in tanks, bodywork of vehicles.
25. -Epoxy resins They are good
electrical insulators, resistant to humidity and high temperatures.
We can used it in varnishes, coatings for word, plastics, and electrical and electronic
systems.
26. -Thermoplastics: They are soft and you can deformed with heat
They are divided in some groups:
transparent, tough, resistant to mechanical stress and oils
Polyethylene terephthalate Uses for carbonated beverages, oils, water, chemical products
Objects made of polyethylene terephthalate are marked with
these symbol
Tough and resistant to mechanical stress and chemical agents.
Polycarbonate Fabrics, household utensils, bearings, gears, screws, household appliance
parts, and electrical connectors.
Objects made of polyamide do not have a specific symbol
27. It is fireproof, and resistant to chemical products
and high temperatures.
Teflon or Polytetrafluoroethylene
Nonstick coatings, joints, and insulation for high-temperature
cables
28. *Elastomers: They are materials that are very elastic.
They are impermeable and a good electrical and acoustic insulator.
We use them for natural rubber products.
-Elastomers is divided in several groups:
It is resistant to organic liquids is impermeable
and a good electrical and acoustic insulator.
Synthetic rubber Tires, solid wheels…etc
In 1887 John Boyd Dunlop,he was an Scottish veterinarian, and he
invented the first air chambers for bicycles of the time and these is
how tires were invented.
