AS level Product Design Unit 2 Polymers AS level Product Design Unit 2

Synthetic Polymer Categories Long chain polymers Crosslinked polymers Thermoplastics Thermosetting Plastics Elastomers Semi-crystalline amorphous Synthetic Polymer Categories

Properties Chemical resistance Transparent (see through) Water absorption UV resistance Impact resistance Tensile strength Light weight Rigid Brittle (easy to shatter / break) Opaque (solid colour) Hard Translucent (slightly see through) Recyclable Properties

Thermosetting Plastics Thermosetting plastics (eg Araldite) are highly linked One way process – cannot be reversed Will not soften with heat EPOXY RESIN Araldite is a trade name for a resin based polymer The resin is mixed with an activator to start curing Urea formaldehyde high heat distortion temperature, low water absorption, mould shrinkage, high surface hardness Bonds MDF Phenol formaldehyde Used for light switches Thermosetting Plastics

Thermoplastics Acrylic PVC (Polyvinyl chloride) Paint, Point of sale displays Food & pharmaceutical packaging Baths, Car lights HDPE (High Density Polyetherlene - PE) Polypropelene (PP) packaging and labeling Bottles (biggest application) Polystyrene (PS) milk bottles (largest bottle sector) Packaging trays, egg boxes, lids LDPE (low Density PE) Styrofoam Supermarket carrier bags Isulation, modelling Packaging film (eg. cling film) Washing up liquid bottles PET (PE Terephthalate) fizzy drinks bottles (Carbonation makes HDPE unsuitable) Thermoplastics

Material Properties: PET Very light Can stand high tensile stress hard, stiff, strong absorbs very little water good chemical resistance (except to alkalis) Medium resistance to UV most commonly recycled plastic drinks bottles are made from PET Can degrade & become discoloured during heat treatment Adds an unwanted flavour to food (can be compensated for at addition cost) Min Temp: -500C Max useful Temp: 1700C Melting point: 250oC. Material Properties: PET

Material Properties: HDPE Excellent for any food related products Not microwaveable Machines extremely well (cut, bond, drill etc.) Good chemical resistance Good impact resistance light weight Poor UV tolerance very low moisture absorption high tensile strength Not a good candidate for gluing. Primarily used for blow moulding Colours fade over time Min Temp: -1000C Max temp: 1100C Melting point: 1300C Applications Milk bottles trays and tanks pipe fittings, wear plates, hinges cutting boards. Material Properties: HDPE

Material Properties: PVC Transparent Is typically coloured to make opaque Good UV resistance Excellent chemical resistance glueable and weldable easily machine able & heat bends nicely Stiff Tough Hard Min temp can be reduced down to -400c by adding plasticizer Makes PVC suitable for hose pipes etc Max Temp: 600C Min Temp: -250C Material Properties: PVC

Material Properties: LDPE Lower density & chemical resistance than HDPE More transparent than HDPE Less expensive than HDPE Colours fade over time Poor UV tolerance Very soft & pliable Max temp 700c Min temp -50oc Melting point 1200c Material Properties: LDPE

Material Properties: Polypropelene (PP) Poor UV resistance Translucent Rigid Very light Excellent chemical resistance food storage applications Medical applications (syringes) Carpets Microwaveable Max temp 1350C Min temp 00C Melting point: 1700C Material Properties: Polypropelene (PP)

Polystyrene & EPS Flammable Excellent thermal insulation Solid: Used in fridge linings Solid: Light, Hard, Stiff, Brittle Expanded: Light, Bouyant, Crumbles Min temp: -400C Max temp: 600c Polystyrene & EPS

Material Properties: Acrylic Trade names: perspex & plexiglass Weather resistant (Can withstand sunlight for long durations) Difficult to recycle Can be done but is very expensive (not cost effective) Stiff (Flexible compared to glass) Less breakable than glass Scratches easily brittle Resistant to most chemicals and industrial fumes Can be cut by various methods Corrosion resistant Good electrical insulator Min Temp: 50C Max temp: 410C Material Properties: Acrylic

Some acrylic Products

Styrofoam is a trademarked brand of closed-cell extruded polystyrene foam currently made for thermal insulation and craft applications. Styrofoam is composed of ninety-eight percent air, making it light weight and buoyant Styrofoam

Issues Safety Many chemical plastisizers contain oestrogen Gender bending chemical Some plastics (eg. PET) degrade & emit cancerous material over time Life Cycle Carbon based plastics take thousands of years to degrade Biodegradeable plastics are being researched now (covered in A2) Sustainability Today: a 500ML water bottle takes 100ml of crude oil to produce (+ energy to manufacture) Recyclable by re-heating Energy cost Contamination is a big issue Some are easier than others Issues

Issues Energy for manufacture All polymers (apart from elastomers) require heat to make them plastic All plastics must be sorted and washed before being recycled Where does this energy come from ? Plastic is itself a fuel and can be incinerated Toxic fumes are a consequence Issues

Task Create a table with the following headings: Polymer, Aesthetics, Properties, Products, Advantages, Disadvantages. Task

Task HDPE LDPE PET PVC Acrylic PP PS Opacity etc Polymer Aesthetics Properties Products Advantages Disadvatages HDPE Opacity etc Chemical resistance etc LDPE PET PVC Acrylic Stryrofoam PP PS Task