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PLASTICS, TEXTILES, STONES AND CERAMICS

UNIT 43º ESO BILINGUALIES MIGUEL ESPINOSATECHNOLOGIES

PLASTICS, TEXTILES, STONES AND CERAMICS

-ORIGIN

-PROPERTIES

-TRANSFORMATION

PLASTICS

-PHYSICAL

-ECOLOGICAL

CLASIFICATION

THERMOPLASTICSTHERMOSTABLE

ELASTOMERS

FORMATION TECHNIQUES

-EXTRUSION

-LAMINATION

-VACUUN FORMING

-MOULDING

SHAPING AND FINISHING TECHNIQUES

-CUTTING

-PERFORATING

-TRIMMING AND TRIMMER

JOINING PLASTICS

-TEMPORARY UNIONS-PERMANENT UNIONS

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1. PLASTICS

1. ORIGIN� PLASTICS, FOR THEIR PROPERTIES,

AVAILABILITY, TRANSFORMATION PROCESS AND PRICES, ARE THE MATERIAL OF THE FUTURE.

� PLASTICS ARE MATERIALS FORMED BY POLYMERS.

� THE POLYMERS IN PLASTICS ARE MADE FOR LONG CHAINS OF CARBON ATOMS.

1. PLASTICS

� CLASIFICATION OF PLASTICS DEPENDING ON THEIR ORIGIN:

- NATURAL PLASTICS: are obtained directly from raw vegetable materials. Examples: cellulose and latex, from animal protreins.

- SYNTHETIC PLASTICS: are made from compounds extracted from petroleum, natural gas and coal. Chemical process.

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1. PLASTICS

� The transformation of these raw materials and compounds into plastics is called polymerisation.

� Different plastics?- During the manufacturing process, we can add

materials such as fibreglass, textile fibres, paper, silica and sawdust to reduce production costs, and to develop certain characteristics.

- We can incorporate chemical additives to increase flexibility and to strengthen the polymers, and we can add pigments to give colour to the plastics.

1. PLASTICS

2. PROPERTIES OF PLASTICS� The properties of plastics depend on their type and

their composition.� Similar characteristics of many plastics:- Strength- Elasticity- Rigidity- Flexibility* Although they vary from one type to another.

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1. PLASTICS

� Common properties to the majority of plastics:- mechanical: malleability, ductility, mechanical

resistance.- Acoustic: acoustic insulation.- Electrical: electrical insulation.- Thermal: thermal insulation.- Other properties: low density, impermeability.Activity: look for the definition of each property (12: Strength,

Elasticity, Rigidity, Flexibility, mechanical: malleability, ductility, mechanical resistance, Acoustic: acoustic insulation, Electrical: electrical insulation, Thermal: thermal insulation, Other properties: low density, impermeability)

1. PLASTICS

3. ECOLOGICAL PROPERTIESPlastics contaminate a lot!!!We can recycle plastics.There are three recycling processes: - Chemical recycling: we apply chemical processes to

make new materials from the original components of plastic residues.

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1. PLASTICS

- Mechanical recycling:We make new products from plastic granules. The

process has five stages:1. Separation and crushing � according to their type.2. Floating. Wash and dry (centrifugal force).3. Agglutination. The material is compacted and then

incorporated into other materials.4. Extrusion. To melt the material � extruded into long

filaments.5. Pelletising. The filaments are then reduced to

granules that we call pellet.

1. PLASTICS

- Energetic recycling. We can incinerate plastics and the energy that is produced and used in industry, for heating or producing electricity.

* Biodegradable: the majority of plastics are not.

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2. CLASSIFICATION OF PLASTICS

2.1 Thermoplastics

2.2 Thermostable

2.3 Elastomers

2. CLASSIFICATION OF PLASTICS

Classification according to its structure.

2.1. Thermoplastics

From compounds acquired from petroleum.

When we heat them, they become soft���� which allows them to

be formed into different shapes.

The heating and cooling process can be repeated many times.

Made up and formed of weakly molecular chains.

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2. CLASSIFICATION OF PLASTICS

Thermoplastics examplesPVC: Cloruro de polivinilo *

Strong. Waterproof. Durable.

Uses: tubes and pipes. Shoe soles. Gloves.

Waterproof clothing. Hosepipes.

PS: Poliestireno *. Two types:

a) Hard: Transparent. Can be coloures.

Uses: CD cases. Coat hangers.

Dairy products containers. Egg boxes.

b) Expanded (porexpan): porous. Soft.

Uses: packaging. Thermal and acoustic insulation.

PE. Polietileno. Two types:

High density (HDPE)*: Rigid. Resistant. Transparent.

Low density (LDPE)*. Soft. Light. Transparent.

Uses: transparent packaging film. Bags. Cups and plates.

* ���� Recyclable plastic

2. CLASSIFICATION OF PLASTICS

Thermoplastics examplesPP. Polipropileno *

Flexible. Resistant to chemicals. Hard surface.

Uses: bottles and containers. Ropes. Bags.

Metacrilato*. Plexiglas. Transparent.

Uses: car headlights. Windows. Illuminated signs.

Goggles. Watches.

Teflón* non-stick. High heat resistance.

Uses: kitchen utensils. Paints. Aircraft and rocket exteriors.

Celofán (Biodegr.)

Transparent. Flexible. Resistant. Shiny. Adhesive.

Uses: packaging. Wrapping.

Nailon o Poliamida. Translucent. Shiny. Resistant.

Flexible. Waterproof.

Uses: fabrics. Toothbrushes. Tennis racket strings.

* ���� Recyclable plastic

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2. CLASSIFICATION OF PLASTICS

2.2. Thermostable plastics

Made from compounds derived from petroleum.

Formed by strongly-linked chains running in different directions.

When heated, they become soft and can be shaped.

When cooled, they cannot be remoulded by applying heat.

2. CLASSIFICATION OF PLASTICS

Thermostable plastics:

Poliuretano (PUR)

Porous and flexible. Soft and dense.

Elastic and adhesive.

Uses: foam rubber for cushions. Sponges.

Thermal and acoustic insulation.

Glues and varnishes.

Resinas Fenólicas (PH). Baquelitas

Dark colours. Electric insulator.

+Fibreglass�Shock resistant.

+Asbestos (Amianto)� Heat resistant.

Uses: kitchen utensil handles.

Covers for electrical insulation.

Electric plugs and switchs.

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2. CLASSIFICATION OF PLASTICS

Thermostable plastics:

Melanina

Light. Hard resistant. Tasteless and odourless.

Thermal insulator.

Uses: Small electric objects.

Thermal and acoustic insulation.

Kitchen surfaces. Plates and food containers.

Resinas de poliéster (UP)

Heat resistant (200 ºC)

Reinforced by fibre-glass for strength

and rigidity.

Uses: crash helmets. Bodywork for cars and

boats. Fishing rods.

2. CLASSIFICATION OF PLASTICS

2.3. Elastomers

Made by vulcanisation.

Vulcanisation: Charles Goodyear (1800-1860). Mixing sulphur and

rubber to 160 ºC� become hardness, resistance and durability

without losing its natural elasticity.

Formed by chains linked laterally and then folded over

themselves.

Hard, resistant and very elastic – stretching easily under force..

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2. CLASSIFICATION OF PLASTICS

Elastomers:

Caucho natural (natural rubber)

From latex. Resistant and inert.

Uses: thermal and electrical insulation.

Mattresses. Tyres.

Synthetich rubber (polymer)

From petroleum. Resistant to chemicals.

Uses: tyres, steering wheels. Gloves.

Mattresses.

Neopreno

From synthetich rubber. Harder and more resistant

than synthetich rubber. Waterproof.

Uses: diving suits. Hosepipes. Gloves.

Mattresses: colchones Tyres: neumáticos - Wheels: ruedas steering wheels: volantes

3. FORMATION TECHNIQUES

� The plastic used to manufacture objects is available in three

different forms: powder, granules and resins.

� We can use different formation techniques depending on

the type and use of the plastic.

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3. FORMATION TECHNIQUES

� EXTRUSION

� This technique has four steps:

1. We put thermoplastic, in granular form, into a previously heated

cylinder.

2. We apply pressure by means of a large, rotating screw, which forces the

melted material out, through 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.

Used to form: wrapping, lining for electric cables, tubes and pipes.

extrusiónNozzle: inyector

Feeder: alimentador

Wrapping: envoltura

3. FORMATION TECHNIQUES

� LAMINATION� Thermoplastic produced by the extrusion method is passed through a

series of hot cylinders to produce sheets of varying thickness.

� We can produce different finishes (glossy, matt or textured), depending

on the outer coating applied by the final cylinder.

� Applications: kitchen furniture, worktops, to cover surfaces of kitchen

and drawers.

calandrado.JPG

calandrado 2

Sheets: láminas, hojas.

Thickness: grosor

Glossy: liso, brillante.

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3. FORMATION TECHNIQUES

� VACUUM FORMING

� For plastic sheets with a large surface.

� Steps:

1. Put a thermoplastic sheet into a mould.

2. Use a heater to heat the mould and soften the plastic.

3. Extract the air below the sheet so that the plastic is pulled against the

inside walls of the shaped mould, and the desired form is created.

4. Leave the mould to cool, then remove the object.

Applications/ Used to form: bathtubs, dashboards, shop signs and egg

boxes.

Conformado al vacío1 Conformado al vacío2

Vacuum forming: conformado al vacío

Bathtubs: A bathtub is a long, usually rectangular container which you fill with water and sit in to wash your body.

Dashboard: salpicadero

3. FORMATION TECHNIQUES

� MOULDING

A hollow container or mold with the final form of the wished product IS

used as counterfoil in order to make the plastic acquire the form of

the above mentioned interior surface

There are three principal techniques:

1. Inyection

2. Blow moulding

3. Compression

Counterfoil: matriz

To spill: verter

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3. FORMATION TECHNIQUES

� Blow moulding

1. We put a tubular-shaped piece of

plastic (from extrusion) into a

hollow mould which has the same

shape as the object that we want

to make.

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.

Used to form: hollow objects (bottles and flasks)

Hollow: object that has an empty space or cavity inside. Flasks: frascos.

3. FORMATION TECHNIQUES

� Injection moulding

1. We inject melted material into a mould.

2. When the material has cooled and solidified, we extract it from the

mould.

Used to form: domestic utensils such as buckets and containers, vehicle and

aircraft components.

Bucket: round container with a flat botton for water and other fluids.

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3. FORMATION TECHNIQUES

� Compression

1. We put thermostable plastic in granular form into the base of a cavity

mould.

2. The outer part of the cavity mould, shaped the same, is closed to

compress the material inside. Then we heat it and it becomes soft and

malleable.

Used to form: different types of containers, machine bodywork and electrical

appliances.

3. The plastic adapts to the shape of the

cavity between the two parts of the

mould.

4. We extract the object when the plastic

has cooled and solidified..

4. SHAPING AND FINISHING TECHNIQUES

We can use different tools and machines to finish the plastic objects that

have made.

Principal techniques: cutting, perforating, trimming and filing.

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4. SHAPING AND FINISHING TECHNIQUES

CUTTING:

- Cutter

- Scissors

- Steel bit

- Feetsaw

- Jig saw

�To cut sheets of different thickness, depending on

their hardness.

�To cut soft, thin and flexible sheets.

�To cut sheets less than 1 mm in thickness.

�To cut soft, low density plastics. Can make straight,

slanting and curved cuts.

� to cut very large sheets of plastic, and rigid plastics

in general. Can make straight, slanting and curved cuts.

4. SHAPING AND FINISHING TECHNIQUES

CUTTING

- Power press

- Hot metal thread trimmer

� to cut flat sheets of low density plastic. Makes

simple objects by applying preasure.

� to cut sheets of soft thermoplastic. (poliestireno

expandido or porexpan)

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4. SHAPING AND FINISHING TECHNIQUES

PERFORATING:

- Drill bit�Tool that makes holes in plastics.

Consists of inserting a long, thin, round and

threaded piece of metal into the head of the

machine that envolves high speed for cutting

holes.

4. SHAPING AND FINISHING TECHNIQUES

TRIMMING AND FILING:

- Lima y Escofina

A file has a rough surface.

Used to finish the surfaces and edges of hard materials.

A rasp has an even rougher surface, covered with “teeth”.

Used to finish the surfaces and edges of soft materials.

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5. JOINING PLASTICS

Una vez manipulados, los plásticos pueden juntarse mediante uniones

desmontables o fijas.

5.1. Uniones desmontables

Permiten la unión y separación de las piezas mediante elementos roscados

que impiden la rotura del plástico.

Son:

-Tornillo pasante con tuerca.

-Tornillo de unión.

-Enroscado.

5. JOINING PLASTICS

5.2. Uniones fijas

Se usan cuando no se prevé la separación o desmontaje ya que no se

pueden separar sin que se produzca la rotura de los elementos.

Los plásticos se pueden unir mediante adhesivos o soldadura.

-Adhesivos: unión permanente cuando se interpone entre dos

superficies. Pueden ser resinas, cemento acrílico o adhesivos de

contacto.

-Soldadura: unión por medio de calor y presión. Es muy utilizado el

método de mordazas calientes.