PiXL Independence. Technology Answer Booklet KS4. Plastics Contents: Answers I. Multiple Choice Questions- 10 credits each

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1 PiXL Independence Technology Answer Booklet KS4 Plastics Contents: Answers I. Multiple Choice Questions- 10 credits each II. III. Knowledge and Application 10 credits each Exam Style Questions 100 credits each 1

2 1. Plastics are a non-renewable resource created from: a. Oil and gas b. Oil c. Coal d. Gas 2. Plastics are created by a. Polymerisation b. Cross links c. Monomerisation d. GRP 3. Name two plastics families a. Thermosets and Chain Cross Linked Polymers b. Thermoplastics and non-thermoplastics c. Thermoplastics thermosets and Polymers d. Thermoplastics and Thermosets 4. If thermoplastics are heated they will a. Stay rigid b. Soften and melt c. Get stress marks d. Burn straight away I. Multiple Choice Questions 5. The reason thermoplastics soften and melt when heated is a. Because the electrostatic bonds called Van Der Waals Forces weaken and then disappear b. It never has any cross links c. The polymer chains react with each other to create movement d. It is a smart material 6. Thermosets have permanent cross links and are bonded by covelant bonding a. True b. False c. Only when heated d. Only when they are cold 7. Thermosets are normally two parts mixed -one being a catalyst- and 'go off' as a chemical reaction a. True b. False c. Exothermic d. Endothermic 8. Urea formaldehyde is used for plug sockets because a. It can be produced in many colours b. It is stiff tough and resistant to heat c. It will not burn d. It is cheap 9. What thermoset plastic laminate are is put on top of chipboard on kitchen work surfaces a. Epoxy resin laminate b. Urea formaldehyde c. Toughline thermoset polymer d. Melamine Formaldehyde 2

3 10. UPVC is used for double glasing window frames because a. It is weather and chemical resistant, stiff, hard and tough b. Easy to fit for the workman c. Comes in lots of colours d. More durable than wood or metal 11. Expanded polystyrene is used for disposable coffee cups because a. It is made from vegetable oil b. It is lightweight and a good insulator of heat c. It is white and that makes people think it is hygienic d. It is easily recyclable 12. PET is used for water bottles because a. Milk bottles are made from the same thermoplastic so it is cheaper b. It is environmentally friendly c. It is food safe, clear and extrusion blow moulds well d. It is white 13. Safety helmets are made from ABS because a. It is a thermoset and therefore is good with heat b. It is yellow c. It is a smart material and changes colour when hot for safety d. It is tough, hard -scratch resistant- and has a good finish 14. What is plastic memory? a. A shape memory alloy b. The ability of a plastic sheet to return to its original shape when reheated c. An injection moulding process d. The definition of a thermoset plastic 15. Acrylic is used for shop signs because a. It is cheap b. It has a high surface finish, comes in lots of colours and is durable outdoors c. It is not brittle d. It is scratch resistant 16. In GRP the glass fibre matting is added to the polyester resin to a. Make it malleable b. Add stiffness and toughness and take away brittleness c. Make it as good as carbon fibre d. Make it stronger 17. Nylon is greasy and self-lubricating and is therefore used for a. Bushes and bearings b. Washing-up bowls c. Clothes d. Nuts and bolts 18. Plasticisers, foamants, fillers and stabilisers are all examples of what a. Thermoplastics b. Additives for polymers c. Types of polymer d. Thermosets 3

4 19. Thermoplastics have to be recycled with the exact same thermoplastic. True or false a. No you cannot recycle thermoplastics you can recycle thermosets b. Yes because they have very different properties and chemical structure c. No you can put them all together no problem they are very similar d. Yes because the supermarkets make each different plastic a different colour to differentiate them 20. Plastic bottles are becoming a real problem. How do we deal with this? a. Limit ourselves to one water bottle a week b. Have one bottle we always refill and stop buying bottled water c. Use glass bottles instead d. Don' t bother it is fine II. Knowledge and Application 1. State if melamine formaldehyde is a thermoplastic or thermoset polymer Thermoset a. Describe the physical properties of melamine formaldehyde Hard, tough, food safe, heat resistant b. Name two products made from this polymer Kitchen work surfaces laminate; school desk laminate; cups, beakers and plates (kids) 2. Describe the main stages of producing GRP moulding such as a bath or boat hull. Make mould; male or female Add surface of high surface finish and buff Add mould release agent Mix gel coat with catalyst and pigment Pour on gel coat Roll in fibre matting Roll on fibre tape in points of stress such as edges Leave to set Remove from mould Trim and finish 3. This plug socket is made from which material? Melamine Formaldehyde Epoxy Resin Urea Formaldehyde 4. Describe the physical properties, of the thermoset plastic above, which make it suitable for electrical fittings and domestic appliance components Stiff, hard, heat resistant, electrical insulator 4

5 5. Epoxy resin is a thermoset polymer and is used for what? As a two-part adhesive and car body filler; for kitchen work surfaces; it is another name for carbon fibre 15 Marks Plastics Knowledge and Application Part 2 1. This plastic water bottle is made from PET. State if this is a thermoplastic or thermoset. Thermoplastic a. State two physical properties that make it suitable for a drinks bottle Clear, cheap, food safe, alcohol safe, cooking oil safe; high impact resistance b. Describe how this bottle will be recycled With only PET, separate rubbish, send to single stream recycling plant, read symbol on bottom, shred and recycle 2. This double-glazed window frame is made from UPVC a. It is made by: Extrusion Injection moulding b. State two physical properties that make it suitable for a window frame Weather and chemical resistant, stiff, hard, tough 3. This packaging is made from expanded polystyrene a. State two physical properties that make it suitable for this purpose Absorbs impact; lightweight; can be moulded in to complex shapes b. Is this a thermoset or thermoplastic? Thermoplastic c. Can this polymer be recycled? No 4. The cable flex covering shown in the picture is made from low density polythene. a. Name two properties of LDPE that make it suitable for this job Tough, flexible, electrical insulator b. Why is it important that pigment is added to the wires during the manufacturing process and not after as per a wood or metal? So that the live, neutral and earth wires can be differentiated; if it were added after it could crack and split when bent and come off; it needs to be inside the plastic; plastic is unique in this way 5

6 5. The hard hat safety helmet is made from ABS a. Name two properties that make ABS suitable for this product Tough; high impact resistance; can mould complex shapes; colours well b. What process is used to make it? Injection moulding 6. The cog wheel is made from nylon a. Is this a thermoset or thermoplastic? Thermoplastic b. Name two properties that make it suitable for this product Greasy (self-lubricating); tough; impact resistant; hard wearing 22 Marks III. Exam Style Questions Polymerisation and General Plastics: 1. Describe what a polymer is A series of monomers; polymerised into a chain 2. Describe what makes thermoplastics unique They can be heated and softened; this can be repeated any number of times; a plastic sheet will attempt to return to its original shape if reheated (plastics law); when cools return to full hardness and stiffness 3. Describe the physical properties of a thermoset plastic Tough; hard; goes off with a chemical reaction; sets once only 4. Explain how the bonding in a thermoplastic changes when it is heated Cross links are present when cold; these are Van der Waals forces of electrostatic attraction; when heated these weaken and then disappear and the chains can move over each other. Two marks for quality of written English; use of Point, Evidence, Explain; including reference to other materials 6

7 5. Explain the type of bonding in a thermoset plastic and how it is resistant to heat The bonds formed are permanent covalent bonds; therefore when the thermoset is heated there is no reaction: it says set. The crosslinks are permanent; it will eventually burn if a high enough temperature is supplied 6. Which additive is used to give the polymer the necessary physical properties for these woggle floats? Stabiliser; Plasticiser; Foamant; Pigment or Filler 7. Describe the difference between an adhesive and a cement A cement melts the two parent plastics together into a weld; and adhesive sticks them together a. Name a cement used to join (weld) thermoplastics Tensol 20 Marks 7

8 Discussion, Justification and Evaluation of Plastics Questions should be answered using point evidence explain to achieve higher marks. 1. The Water bottle shown has a number of features: a sports cap; a crumpleable body; symbols on the bottom; safety seals and others. a. Name and justify the use of a thermoplastic for the body of the bottle PET; food safe; see through; oil safe; extrusion blow moulds well b. Outline the pros and cons of this material in terms of sustainability Negative: Non-renewable resource; has to be recycled with exact polymer; non-biodegradable Positive: Widely recycled; all water bottles made from this so easy to separate at plant; recycling symbol clearly on display c. Name and justify the use of a thermoplastic for the cap of the bottle ABS/PP; injection moulds well; tough; food safe; oil safe; can be made very accurate for snap fittings 2. a. Name the process used to manufacture the body of the bottle and justify the use of this over another, named, plastics process Extrusion blow moulding Only process to produce a hollow product; can produce a very thin product due to extrusion of parison; very accurate mould due to two part; can be done in volume unlike rotational moulding; injection moulding would not work as generally produces solid mouldings. Four marks for fact and two for argument and structure; Point; Evidence; Explain b. Name the process used to manufacture the sports cap and justify the use of this over another, named, plastics process Injection moulding Good for small complex parts; accurate to produce snap fittings; very good (cheap) for volume production; vac forming can t produce this 3d shape without draught angles; press forming is too slow Four marks for fact and two for argument and structure; Point; Evidence; Explain 3. a. Explain the purpose and meaning of the symbols on the bottom of the bottle Recycling symbols; international recycling symbol three arrows; contains a number to signify the type of plastic 1-7 resin code; in this case a 1; helps in the single stream recycling centre; b. Evaluate the effectiveness of the symbols in the recycling system where you live Four marks available for a good description of local recycling. Including: separation; washing/rinsing (at end of washing up not in clean water); knowledge of single stream recycling plant; shredding 4. A bus shelter uses cast acrylic -otherwise known as Plexiglass - as the material to cover its advertising hoardings a. Justify the use of this material Four marks for content: tougher than glass for impact resistance; good optical properties; can be machined (drilled at corners); scratch resistant (but not as good as glass); if does break not too sharp 8

9 5. Carbon fibre and GRP are composites. Explain, in detail, for both materials how the addition of the fibres adds to the physical properties of the material in the desired way Six Marks for knowledge GRP: Glass Reinforced Plastic or Fibre Glass; gel is polyester resin or styrene; thermoset; addition of messy mat stiffens; needs to be in a 3d shape with flanges for stiffness; addition of more woven matrix type tape around the flanges and stress areas for extra stiffness. Examples: sports car bodies; boat hulls; water slides- this material is now a bit 20 th century. Carbon fibre: polymer gel is Epoxy Resin; thermoset; gel on own will crack and split; addition of woven mat stiffens; very stiff; results in very very high strength to weight ratio. Uses F1; road bikes Four marks for quality of written English; use of Point, Evidence, Explain; justification including reference to other materials (Kevlar) and comparing and contrasting the two materials 50 marks 9

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