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Engineering Polymers, Energy 5
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- 1Polymers, Composites, Ceramics, TimberA51M AL1
- 2Define a polymer and identify the 2 main types?- This is a type of material made from a large number of chemical units bonded together.
- Most are synthetics (man-made) are made from crude oil.
- The 2 main types of polymer are thermoplastics and thermosetting polymers. - 3Why can thermoplasticsbe recycled?- Thermoplastics consist of long chains of molecules of repeating chemical parts.
- The chains are only weakly attacthed to each other.
- The weak links mean that thermoplastics are relatively ductile.
- This means that they become softer and flexible when heated.
-They can be shaped when they are hot, and they harden into the new shapes as they cool.
-They can be recycled by melting. - 4Identify and compare a variety of thermoplastics.-ABS -strong,rigid,toug - used on plastic toys.
-Acrylic- good optical properties, hard wearing, will not shatter- bath tubs.
-Nylon -good resistance to wear, low friction,ductile,durable- used on gears.
- High impact polystyrene- HIPS is tough and has impact strength used for signs.
-Expanded polystyrene- light weight and can absorb an impact, insulator- Used for packaging and foam cups.
-Polypropylene- hard,lightweight,chemical resistance- used in food containers.
- polycarbonate- high strength,high toughness, heat resistant- used on safety goggles. - 5Explain why thermosetting plastics cannot be recycled?- Thermoplastics have more strong links formed between the individual molecule chains.
-The thermosetting plastics are thus less ductile, more rigid, and harder.
- When heated they do not soften but burn.
- They therefore cannot be recycled. - 6Identify and compare a variety of thermosetting plastics?- Epoxy- high strength,stiff,brittle,excellent tempreutre,chemical and electrical resistance- used for PCB.
-Polyester resin- good strength,stiff,brittle,good tempreture,chemical and electrical resistance,low cost- suitcases.
-Urea formaldehyde- stiff,hard strong,insulator-used in electrical sockets
-Melamine formaldehyde- stiff,hard strong- used for laminate coverings. - 7Explain what type of plastic to use for a bowl to heat food in a microwave oven?Must have excellent tempreture resistance. Most thermoplastics would therefore be ruled out, except for polycarbonate, which also is tough and so would resist impact incase it dropped and could be made using injection moulding. It could also be made from thermosetting polymers such as epoxy and polyester resin, though these may be more expensive to manufacture.
- 8Name 2 thermoplastic polymers?ABS, PVC, acrylic, polystyrene, polycarbonate, nylon.
- 9What is the difference between a thermoplastic and a thermosetting polymer?- Thermoplastics consist of ling chains of molecules with weak links between them.
-Thermosetting polymers consist of ling chains of molecules with strong links between them.
-Thermoplastics are therefore ductile. They also soften when heated, meaning that they can be reshaped and recycled.
-Thermosetting polymers are rigid,and cannot be reshaped-they burn when reheated- and cannot be recycled. - 10Why is sediment deposited?- Rivers or waves lose their energy.
- This results in the depositing their sediment load. This leads to the formations of river beaches on the inside of river bends as well as coastal beaches. - 11Define what a composite is?- A composite is a type of material that is made by combining two or more different types of material which remain physically distinct within its structure (an alloy is not a composite).
- 12What are the main functions of the types of material within a composite, giving examples?A typical composite contains two materials:
-The function of one of the materials is the reinforcement to provide strength.
- The function of the other material is the matrix, to hold the reinforcement together.
- Common reinforcments include strands,fibres,layers and particles.
-For example, reinforced concentrate consists of strands of steel bars held together in a matrix of concrete. - 13Identify 5 other common composite materials and describe their typical uses?- Carbon-fibre reinforced polymer (CRP)- high strength to weight ratio,expensive -used on racing bicycles ,helmets.
-Glass-reinforced plastic (GRP)- high strength to weight ratio,good chemical resistance, cheaper but weaker than CRP- used on canoes, water tanks.
- Plywood- rigid,good strength - furniture, exterior construction.
-Medium density fibreboard (MDF) - smooth, uniform and even sheet material,rigid,easily machined and finished- interior construction. - 14Explain why composites are normally not recycled?- Most composites are made using the moulding process.
-The different materials are added together to from the required shape.
-These different materials are extremely difficult to seperate.
-Therefore, they are usually not recycled. - 15Explain why structural timber is usually made from softwood, giving examples?- Softwood trees, or coniferous trees grow faster than harwood trees.
-Therefore they are cheaper to produce.
- Therefore they are used more in construction.
-Examples include pine, cedar and spruce.
-Timber is provided in the following standard forms : square,planks,boards.
- Timber can be rough sawn or planed all round. (PAR-smooth). - 16What are ceramics and when are they used in engineering?- Ceramics are a type of material that is typically an oxide, nitride,or a carbide of a metal.
-They are used in building materials (concrete) to cutting tools (tungsten carbide)
-They have good compressive strength.
-They have low tensile strength, very low ductillity and are brittle.
-Made by moulding processes then fired in furnaces (thick clay pottery)
-Not usually recycled due to high costs of energy to melt them. - 17Explain why a company may buy in a standard size of material.?- The cost of a product includes the cost of the material and changing its shape into the product.
-Marerials are available in a wide variety of standard forms and sizes.
-These are manufactured in large quantaties by the companies that process the raw materials, meaning that they are much cheaper.
-It is therefore much cheaper for a product manufacturing company to buy these standard materials rather than making their own. - 18Factors influencing design of solutionsA51M
- 19What is the engineered lifespan of a product?This is the amount of time that a product is designed to last.
- 20What is planned obsolescence?This is where a product has been designed to last for a set period of time; this may be for buisness or safety reasons.
- 21What are the tree types of planned obsolescence?- Quality- materials in the product are designed to wear out or break down. For example designers could carefully choose materials that will wear out but care must be taken to ensure that failure is not disastrous. Alternativaley it could involve the use pf sealed parts in enclosed compartments that may break down, causing the whole product to be replaced.
-Function- the existing product becomes out of date because new, improved products become available.
-Desirability- The product is designed to go out of fashion. - 22Identify and describe the two types of maintenance?-Reactive maintenance- involves repairing broken parts
-Proactive maintenance- inivolves carrying out actions that will prevent a product from failing. - 23List 6 examples of proactive maintenance?-Lubrication- reduces wear and friction between parts.
-Applying protective coating- prevents corrosion.
-Regular cleaning- removes materials/chemicals that may cause corrosion.
-Adjusting parts- in some products it may be possible to adjust the position of parts/components.
-Replacing parts before they fail- Eg
batteries.
- Using statistics- Eg. by using data on how long something works for before it fails. - 24Addictive manufacturinngA51MAL1
- 25Define addictive manufacturing?A manufacturing method were a part is built up by adding material where it is required.
- 26Describe sintering?-Sintering is a process to make produce from metal powders.
-A mould is filled with metal powder.
-High pressure and then heat is applied.
-The particles of metal powder fuse together.
- Can use it to join metal powders that would not normally mix well when melted. - 27Describe rapid prototyping?-Rapid prototyping involves using addictive manufacturing to make a complete part or component.
- 28Describe fused deposition modelling?-There is rapid prototyping method that prints a part layer by layer using polymers such as ABS, Eg. 3D printing.
- A 3D CAD drawing is created and broken down into a series of layers.
The printing head melts and deposits the polymer layer by layer until the component has been produced. - 29Describe stereolithography?-This is a rapid prototyping method that uses a laser to build up a polymer part.
-A 3D CAD drawing is created and broken down into a series of layers.
- A moveable platfrom is placed in a tank of resin.
-The laser draws each layer on the moveable plate, causing the resin to turn into a hard polymer.
-The plate moves down a tiny bit, more resin flows over the movable plate, the laser draws a new layer, causing the resin to hardern.
-The process continues until the component has been produced, whereupon the part is raised above the resin bath, allowing any liquid resin to drain away. - 30How is electricity generated?• Electricity is generated by causes turbines in a generator to turn
• This usually happens by heating water to produce steam which turns the turbines - 31How can fossil fuels produce electricity?• Fossil fuels are non-renewable energy sources such as oil, gas and coal
• These fuels are burnt in large furnaces to turn water into steam
• The steam turns the turbine in a generator to produce electricity
• These are very reliable and can provide huge quantities of power
• Pollution is a byproduct of this process - 32How can nuclear energy produce electricity?• Nuclear power uses radioactive uranium.
• As the uranium decays it releases energy
• This energy generates heat which is used to turn water into steam to power generators
• The radioactive waste can remain hazardous for many years
• Electricity is provided continually at low cost
• These power stations are very expensive to produce - 33How can wind power produce electricity?• Wind power can turn the propeller blades of a wind turbine to produce electricity
• These are relatively low cost, but only produce electricity when there is wind
• These also require a lot of land - 34How can tidal power produce electricity?• Tidal power can turn the propeller blades of turbine to produce electricity
• More consistent than wind power but expensive to set up
• May adversely affect ecosystems - 3553. How can biomass produce electricity• Biomass are materials that are burnt to provide heat to produce steam for generators
• Much of the biomass would otherwise be waste
• Less efficient than fossil fuels, and pollution is produced - 36How can solar power produce electricity?• This is sustainable
• Cannot generate electricity at night
• Large areas needed for solar panels
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- Flashcards on Engineering Polymers, Energy, created by AsimAli Rehman on 07/08/2019.
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- AsimAli Rehman
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