Plastics.

Plastics

Raw materials that make plastics
Plastics, were first developed in the late 1800’s, and have become the most widely used material in product manufacture. There are hundreds of different types of plastic, though only 15 common ones. There are two main types of plastics: Natural Synthetic There are also two main categories of synthetic plastic: Thermoplastics Thermosetting plastics

Natural Plastics Amber
Amber occurs naturally, and does not need any processing. Amber is actually fossilised tree sap. When the sap oozed from a broken branch, it would often trap insects, and after millions of years became hard. It is commonly used for decorative jewellery today. Amber jewellery Jurassic Park!

Natural plastics Rubber (Latex)
Latex is a natural plastic extracted from ‘Rubber trees’ & is used to make chewing gum, rubber gloves, elastic bands and condoms ! Shallow diagonal cuts are made into the bark, allowing the latex to bleed into a pot attached to the tree. Rubber trees grow in tropical climates, lie South East Asia and South America. The Eden project has some latex rubber samples in the Tropical Bio dome. Watch latex extraction

Synthetic Plastics – Are commonly made from carbon based raw materials like…… crude oil, natural gas coal

Synthetic Plastics C2H4 Ethylene Polymer Van der Waals bonds
These plastics are made in specialised laboratories, factories or production lines. Monomers link together by strong electrostatic forces called ‘Van der Waals Bonds’ to form Polymers. H and C atoms link together… to form a molecule (Monomer) A polymer is a long chain of monomers The process of linking lots of monomers together to form a polymer is called ‘polymerisation’ H H Ethylene Polymer C C H H C2H4 Van der Waals bonds This is an Ethylene Monomer Ethylene Monomers Watch this video about polymerisation and making nylon

Common Properties of plastics
General Properties of ‘Plastics’ Material Property means:- a specific trait of a material, or what it is like or how you would describe it Workability– (how easy it is to cut drill, join a material) – plastics are very workable with a little heat to make them ‘plastic like’ Malleability – (when a material can be reshaped either hot or cold) – plastics are very malleable when hot and some when cold! Density – (the material’s weight/m³) e.g. Styrofoam is 90% air & 10% styrene so it is very light compared to Phenol Formaldehyde a very dense plastic Ductility – ( a material’s ability to be stretched without breaking) – latex elastic bands are very stretchable Common Properties of plastics Toughness – (when a material can withstand impact) e.g. ABS is used for crash hats and is tough Optical properties & colour – (materials natural colours and opacities) e.g. plastics come in colours, translucent, transparent or opaque Elasticity – (when a material can be stretched or bent but can still return to it’s original shape) e.g. elastic bands) Conductivity – (a material’s ability to conduct heat or electrical energy) plastics are a very poor conductor of both Hardness – (a material’s ability to withstand ‘scratching’ and indentation) e.g. nylon is very hard Strength to weight ratio – (when a material can withstand Tension, Compression, Shear, Torsion and Bending) e.g. ABS is a very strong plastic especially when you consider its weight Durability – (a material’s ability to withstand wear and tear and weathering) e.g. water, wind, frosts) corrosion, UV light (e.g. uPVC windows)

Questions

Question What are Synthetic plastics made from?
Carbon based materials (oil, coal, gas)

Question Name two natural plastics? Amber and Latex

Question How is latex extracted? Small diagonal cuts in the tree bark
Latex bleeds from under bark into a cup

Question What is latex used for?
Chewing gum, gloves, rubber bands, condoms

Question What is this called? C2H4
Monomer (molecule) with Hydrogen and Carbon atoms

Question What happens during ‘Polymerisation’?
Ethylene Polymer Individual monomers link together using Van der Waals bonds to form long chains

Question What are the two categories of Synthetic plastic?
Thermoplastic Thermosetting plastic

Question What is another word that describes a material’s maximum stretchiness Elastic Limit

What natural plastic is extracted from Rubber trees
Question What natural plastic is extracted from Rubber trees Latex

Question A material that is resistant to scratching and indentation has what property Hardness

Ability to stretch without snapping
Question What does ductile mean? Ability to stretch without snapping

Question A material that is resistant to wear and tear and weathering is called? Durable

Question If a material is tough – what is it like?
Able to withstand impact and bending without fracture

Question If a plastic is easy to cut, drill and join, what property does it have? Workability

Question Plastics are good conductors of electricity – TRUE or FALSE?
False – they do not conduct electricity

Plastics are poor conductors of heat –
Question Plastics are poor conductors of heat – TRUE or FALSE? True – they are poor conductors of heat and are therefor good insulators

Standard Stock sizes

Standard Stock sizes Plastics come in standard stock sizes, off the shelf from plastic suppliers. Plastic granules for injection moulding machines Plastic powder for powder coating mild steel products Plastic sheets of different sizes and thicknesses for vacuum forming machines e.g. 500mm x 500mm x 2mm thick Round, square or rectangular hollow plastic tubes of different sizes e.g. 25mm diameter x 1metre long Round, squares or rectanglar solid rods of different sizes 10mm x 10mm square x 1 metre long Making plastics in standard sizes, means manufacturers know exactly what is available and can match materials to their machines, like staples to a stapler. Manufacturers can shop around, comparing prices and can easily purchase plastics in standard sizes throughout the world. Standard sizes are easy to stack on shelves, saving storage space

Thermosetting Plastics

Thermosetting plastics
General Properties and uses: Hard and rigid - polymer chains are rigidly linked. Cannot be reshaped or softened with heat, after they have been formed into a shape. Will not melt with heat only burn at extreme temperatures. They are excellent thermal and electrical insulators. They cannot be recycled, making them ‘6R’ environmentally unfriendly. Water proof and chemical resistant e.g. Melamine formaldehyde laminates on kitchen worktops. Most thermosetting products are factory made e.g. urea formaldehyde plugs and light fittings. Some are used in a workshop e.g. ‘casting’ polyester resin to make ‘paper weights’ and jewellery Intro to thermosetting plastics

Melamine Formaldehyde

Thermosetting plastics Melamine Formaldehyde
Look at the pictures below – what properties does this plastic have ? Transparent, Translucent or Opaque Medium light weight Very Durable (Resistance to weathering,) Easily formed in casting / compression moulding Extremely Hard (scratch resistant) Easily coloured with pigments Tough (resists impact) Not Recyclable thermosetting plastic Very Stiff and rigid Water resistant Excellent Heat insulator Excellent Chemical resistant MF picnic ware Decorative work surfaces MF picnic ware

Epoxy Resin

Epoxy Resin (ER) Transparent, Translucent or Opaque Can be cast making paperweights Durable (Resistance to weathering,) Easily coloured with pigments Hard (scratch resistant) Not Recyclable thermosetting plastic Water resistant Excellent Electrical insulator Chemical resistant Commonly used in a two – part glues Two part glue (resin and hardener). When mixed bond metal to metal & plastics. Used to make printed circuit boards for soldering electronic components on to. Epoxy resin glue

Polyester Resin

Polyester Resin Durable (Resistance to weathering, wear and tear) Great for resin cast jewellery Easily coloured with pigments Hard (scratch resistant) Not Recyclable thermosetting plastic Stiff and rigid if reinforced with fibres Water and chemical resistant Commonly used with GRP work Two part glue (‘resin’ and hardener) when mixed together the hardener causes the resin to set hard. Used with flexible ‘Glass fibre’ matting - building up hand made boats using alternate layers of glass fibre and polyester resin Two part Polyester resin can be used to make solid ‘cast’ jewellery, with items cast inside the resin GRP boat building Cast polyester resin jewellery

Phenol Formaldehyde

Phenol Formaldehyde Opaque - black Excellent Electrical insulator Very Durable (Resistance to wear and tear) Very dense and heavy Easily formed into shapes Extremely Hard (scratch resistant) Not recyclable - thermoset plastic Tough (but can crack on large impact) Very Stiff and rigid Water resistant Excellent Heat insulator Excellent Chemical resistance Original early 20th century telephones Saucepan handles Saucepan lid handles

Urea Formaldehyde

Urea Formaldehyde Good strength Colourless polymer Very Durable (Resistance to weathering, wear and tear) Easily formed in compression moulding or injection moulding Extremely Hard (scratch resistant) Easily coloured with pigments Fairly tough Not Recyclable thermoset plastic Very Stiff and rigid Water resistant Excellent Heat insulator Excellent Chemical resistant Excellent Electrical insulator Electric plugs Plug Sockets Wall mounted switches

Questions

Question Name common properties of thermosets? Hard and rigid -
Cannot be reshaped Will not melt with heat. They are excellent thermal and electrical insulators. They cannot be recycled. Water proof and chemical resistant Most thermosetting products are factory made

What is Epoxy Resin usually used for?
Question What is Epoxy Resin usually used for? Two – part glues (resin & hardeners) also PCB’s

What is Polyester Resin usually used for?
Question What is Polyester Resin usually used for? Two – part glues (resin & hardeners) Also used in GRP work, to make shells by bonding glass fibre sheets

Question What is Melamine Formaldehyde usually used for?
Hard, tough, chemical resistant plastic laminates for worktops & tough, strong, stiff durable crockery

Question What is Urea Formaldehyde usually used for?
Rigid, Hard, strong, electrical and heat insulating items

Question What black plastic was used to make telephones but today is mostly used for saucepan handles? Phenol Formaldehyde

Thermoplastics

Synthetic Plastics – ‘Thermoplastics’
General properties and uses: Can be rigid (stiff) in the final state ( eg acrylic, ABS, HIPS). Can be flexible (floppy) in their final state (LDPE) because their polymer chains are loosely laid against each other. Can be heated and repeatedly reshaped. Can be heated, softened & reformed at low temperatures ( polymorph – granules at 60ºC). Ideal for workshop use. Off cuts can be recycled and reused in factory processes. Complex ergonomic products can be manufactured easily in a factory process (eg injection moulding). Pigments can be added to ‘self colour’ the plastic. Good thermal and electrical insulators. Available in sheet, tube, solid rod or granule forms.

High Density Polythene
(HDPE)

High Density Polythene (HDPE)
Thermoplastics - High Density Polythene (HDPE) Look at the pictures below – what properties does this plastic have ? Good Stiffness due to density Easily sterilised up to 130ºC Durable (weathering) Easily coloured with pigments Water proof Tough (Impact resistant) Recyclable thermoplastic Relatively hard (scratch resistant) Chemical resistant Very common all round tough plastic Easily moulded when molten Mopping buckets Milk crates Washing up bowls

Low Density Polythene (LDPE)

Low Density Polythene (LDPE)
Thermoplastics - Low Density Polythene (LDPE) Look at the pictures below – what properties does this plastic have ? Very Flexible plastic Easily coloured with pigments Lightweight Water proof Easily moulded when molten Recyclable thermoplastic Chemical resistant ‘Squeeze’ toys Plastic bags Squeeze bottles Blister packaging

Polystyrene (PS)

Thermoplastics Polystyrene (PS)
Look at the pictures below – what properties does this plastic have ? stiff – does not flex Fairly hard (scratch resistant) light weight Chemical & water resistant Very Brittle (snaps if bent or dropped) Easily coloured with pigments Easily moulded when molten Recyclable thermoplastic CD Cases Disposable cutlery, cups and plates Disposable food containers

Expanded polystyrene (EPS)

Expanded Polystyrene (EPS)
Thermoplastics - Expanded Polystyrene (EPS) Look at the pictures below – what properties does this plastic have ? Low strength Very stiff – does not flex Good impact absorber - packaging Very light (90% air & 10% styrene) Good heat insulator Not Tough (brittle – breaks easily) Good sound insulator Easily moulded when molten Easily sterilised up to 95ºC Easily coloured with pigments Not hard (will scratch - dent easily) Recyclable thermoplastic Chemical & water resistant Heat insulating disposable cups Injection moulded Polystyrene packaging Expanded polystyrene insulation sheets inside walls of buildings EPS packaging EPS uses EPS cups

High Impact Polystyrene
(HIPS)

High Impact Polystyrene (HIPS)
Thermoplastics High Impact Polystyrene (HIPS) Look at the pictures below – what properties does this plastic have ? Very stiff – does not flex Hard (scratch resistant) Light weight Chemical & water resistant Durable (resists wear & tear) Easily coloured with pigments Tough (high impact strength) Recyclable thermoplastic Easily moulded when molten Robust children's toys Fridge linings Lightweight rigid box files

Polyvinyl chloride (rigid PVC)

Rigid PVC (Polyvinyl Chloride)
Thermoplastics - Rigid PVC (Polyvinyl Chloride) Look at the pictures below – what properties does this plastic have ? Chemical & water resistant Durable (Resistance to weathering) Relatively light weight Very Hard Relatively Tough (resists impact) Strong and stiff Good heat insulator Easily moulded when molten Recyclable thermoplastic Easily coloured with pigments uPVC double glazing PVC Water and chemical pipes uPVC double glazing advert Cutting and gluing pvc plumbing

Polyvinyl chloride (flexible PVC)

Flexible PVC (Polyvinyl Chloride)
Thermoplastics - Flexible PVC (Polyvinyl Chloride) Look at the pictures below – what properties does this plastic have ? Low strength (stretches and bends easily) Chemical & water resistant Flexible & rubbery Relatively light weight Durable (Resistance to weathering) Tough (resists impact) Easily moulded when molten Easily sterilised Easily coloured with pigments Good electrical insulator Recyclable thermoplastic Relatively Hard (resists scratching) Cable insulation PVC clothing Hosepipes pvc outfits PVC cable

(Polymethyl methacrylate)
Acrylic (Polymethyl methacrylate)

Thermoplastics - Acrylic (PolyMethyl MethAcrylate-PMMA)
Look at the pictures below – what properties does this plastic have ? A ‘trade’ name of Acrylic is ‘Perspex’ Chemical & water resistant Transparent, Translucent or Opaque Relatively light weight Durable (Resistance to weathering) Tough (resists impact) Relatively Hard (scratch resistant) Easily moulded when molten Stiff – resists bending Easily coloured with pigments Easily sterilised Recyclable thermoplastic Low impact Machine guards & safety goggles Injection moulded plastic cups Acrylic Baths Illuminated shop signs How its made Acrylic Baths

PolyEthylene Terephalate
(PET)

Thermoplastics - PET Look at the pictures below – what properties does this plastic have ? Transparent, Translucent or Opaque light weight Durable (Resistance to weathering, wear and tear) Easily moulded when molten Easily coloured with pigments Relatively Hard (scratch resistant) Recyclable thermoplastic Tough (resists impact) Water resistant Electrical insulator (tape) Excellent Chemical resistance CO ² impermeable (CO2 cannot pass through this plastic) Electricians insulation tape Fizzy drinks bottle (impervious to CO²) Bleach and chemical bottles

Polypropylene (PP)

Thermoplastics - Polypropylene (PP)
Look at the pictures below – what properties does this plastic have ? Happy to bend without breaking Easily sterilised up to 150ºC Lightweight when thin Relatively hard (scratch resistant) Durable (resists weathering) Chemical & water resistant Very Tough (not shatter on impact) Easily coloured with pigments Easily moulded when molten Recyclable thermoplastic Food safe Freezer safe – will not crack at low temp Flip top lids and Click lock lunchboxes –use PP as the plastic is happy bending back and forth repeatedly locking and unlocking Syringes Polypropylene uses Polypropylene Click lock food containers

Nylon (Polyamide)

Thermoplastics - Nylon
Look at the pictures below – what properties does this plastic have ? Durable (Resistance to wear & tear) Chemical & water resistant High melting point Relatively stiff – does not flex easily Good frictional resistance (oily-slippery) Relatively light weight Hard (scratch resistant) Tough (resists impact) Strong Easily moulded when molten Good heat insulator Easily coloured with pigments Easily sterilised Recyclable thermoplastic Mechanisms-Gear wheels Curtain tracks & hooks Bristles on brushes Toothbrush bristles

Polycarbonate (PC)

Thermoplastics - Polycarbonate (PC)
Look at the pictures below – what properties does this plastic have ? Good Chemical & water resistant Transparent, Translucent or Opaque Durable (Resistance to weathering) Relatively light weight Very Hard (scratch resistant) Easily moulded when molten Very Stiff – resists bending Easily coloured with pigments Easily sterilised Recyclable thermoplastic Very Tough (resists high impact) An expensive primary processed material Machine guards & safety goggles car headlamps hair drier casings CCTV camera lenses PC spectacles PC motorbike screens

Acrylonitrile Butadiene Styrene
(ABS)

Thermoplastics - ABS Look at the pictures below – what properties does this plastic have ? Transparent, Translucent or Opaque Electrical insulator Very Durable (Resistance to weathering, wear and tear) Medium light weight Easily moulded when molten Very Hard (scratch resistant) Easily coloured with pigments Very Tough (high impact strength) Recyclable thermoplastic Stiff and rigid with good strength Water resistant Heat insulator Chemical resistant Remote control cars Mobile phone cases PC monitor cases Safety helmets

Questions

Question What does the polymer structure of a thermoplastic look like under a microscope

Question What material is used for these tough, durable, rigid general purpose products ? HDPE

Question What material is used for these squeeze, flexible, lightweight products ? LDPE

Question What material is used for these, very flexible, lightweight, hygienic, food-safe, easily sterilisable products, ? PP

Question What material is used for these rigid, relatively impact resistant household products? HIPS

Question What is so great about this plastic?
Lightweight impact absorbing, thermal & sound insulating, easily injection moulded

Question What is Nylon usually used for?
Flexible & durable clothing, limited friction products (washers, tracks)

Question What material is ideal for these? PC

Question What material is used for these two and why?
PET - CO² impervious and chemical resistant

Question What material is used for these and why?
Polycarbonate (PC) – it is a tough, impact resistant plastic

Question What material is used for these and why?
ABS – it is an extremely tough, impact resistant plastic

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