C2 lesson part one

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C2 lesson part one

  1. 1. Material choices Route map Over the next 12 lessons you will study : Friday 21 October 2011 C2.1 Choosing the right stuff C2.2 Polymers everywhere C2.3 Testing times C2.4 Zooming in End of module test C2.5 The big new idea C2.6 Molecules big and small C2.7 Designer stuff C1.8 Smart materials C2.9 Is it sustainable C2.10 Life cycle assessment C2.11 Life cycle of a synthetic polymer C2.12 Assessing environmental impact
  2. 2. C2.1 Choosing the right stuff Decide whether the following statements are true or false: We will focus on. Friday 21 October 2011 First activity: Think of natural cotton sources from cotton plants. Give three uses for cotton fibres and link those use to the properties of cotton. Give three synthetic materials that are now use routinely instead of cotton ? PLTS Creative thinkers Reflective learners Team workers Effective participators Self managers Independent enquirers <ul><li>Lesson objectives: </li></ul><ul><li>Understand that different materials (natural or man made) have very different properties </li></ul><ul><li>Undesratnd the difference between natural and synthetic materials </li></ul>Numeracy: There are over 25 million different materials or compounds. This list is increasing daily at a rate of 500 new man made materials discovered in laboratories across the World. Literacy: Materials, compounds, physical properties, man – made, synthetic, polymers, monomers, plastic, natural, cotton, silk, wool, hair, nylon, polythene, polyester and fibre We will focus on trying out alternatives or new solutions and follow ideas through
  3. 3. C2.1 Choosing the right stuff Decide whether the following statements are true or false: Introduction: Materials, natural or synthetic (man made) are useful to us because of their physical and chemical properties. We are surrounded by natural and synthetic polymers. Polymer molecules are very long chains of atoms. This is true for natural polymers like silk, cotton, wool and man made polymers like nylon, polythene and polyester. Extension questions: 1: Give the synthetic alternative to the following materials a) glass b) silk c) cotton d) wood and e) Aluminium ? 2: Explain why shoe soles which used to made from leather are now made using plastic and rubber ? 3: Explain why polythene which is made from ethene which is extracted from oil has replaced paper bags across the globe ? 4: Explain why PET plastic have largely replaced glass to store soft drinks and mineral water ? Know this: a: Know that materials are used to make all types of goods and products. b: Know the difference between synthetic and natural materials. Friday 21 October 2011
  4. 4. Key concepts Look at the photograph and information and answer all the questions: Give one use for the following raw materials a) sand b) iron ore c) wood d) crude oil and e) salt (sodium chloride) ? Limestone is used a source of calcium carbonate. This is used to make concrete, cement and glass. What industry used these finished products ? C2.1 a Raw materials A raw  material or substance used in the primary production or manufacturing of a good. Raw materials are often natural resources such as oil, iron and wood. Before being used in the manufacturing process raw materials often are altered to be used in different processes. Raw materials are often referred to as commodities, which are bought and sold on commodities exchanges around the world.
  5. 5. Key concepts t Look at the photograph and information and answer all the questions: Give the raw material that is used to make a) petrol b) brick c) glass and d) cotton ? A Material is anything made of matter, constituted of one or more substances. Wood, cement, hydrogen, air and water are all examples of materials. Sometimes the term &quot;material&quot; is used more narrowly to refer to substances or components with certain physical properties that are used as inputs to production or manufacturing. In this sense, materials are the parts required to make something else, from buildings and art to stars and computers. C2.1 b From raw material into finished products Give one use for the following finished products a) dyes b) plastic PET bottles c) bricks d) nylon rope e) carbon fibre and f) petrol ?
  6. 6. C2.1 b Look at the photograph and information and answer all the questions: Fibres are long filaments. They can be sourced from plant materials for example cotton or silk or be made using reactions for example nylon. There are many uses for these fibres. They can be spun into filaments, string or rope, used as a component of composite materials, or woven into sheets to make products such as paper, felt, cotton and linen. Look at the labels on your clothes and bags. Name two things made from a) cotton b) wool c) nylon d) polyester and e) silk ? Which two cities was nylon discovered in at exactly the same time (The clue is in the name !) ? Explain why synthetic fibres like nylon, polyester and polythene have now replaced natural fibres like cotton and silk…think of things like cost and durability ? Key concepts
  7. 7. C2.1 Plenary Lesson summary: fibres natural chains ropes Friday 21 October 2011 Scientists around the world discover about 500 new materials every day. Things like silly putty and slime may have very trivial uses but other materials like Teflon (non stick) make companies billions of pound globally. How Science Works: Research into plastic like polythene, polypropylene, polycarbonate and neoprene. Look into their uses and their physical properties as synthetic polymers Preparing for the next lesson: Polymers, man made or _________ are made from repeating molecules that are bonded together to form very long ________. These long chains behave like _______ and can be sued to make clothing, ______ and other material goods. Synthetic fibres are used because of their low cost, strength and durability Decide whether the following statements are true or false : False True 3: Cellulose a polymer found in plants is made from glucose molecules ? False True 2: Wool and hair are natural polymers ? False True 1: Nylon was discovered simultaneously in New York and London ?
  8. 8. C2.2 Polymers everywhere Decide whether the following statements are true or false: <ul><li>Lesson objectives: </li></ul><ul><li>Understand that synthetic polymers are designed to meet our needs </li></ul><ul><li>Understand that polymers are very long chains of repeating monomers </li></ul><ul><li>Understand that plastic like polythene are also polymers </li></ul>We will focus on. Friday 21 October 2011 First activity: A mountain climber uses a 11 or 9 mm safety rope as he or she climbs a mountain that is made from nylon and polyester synthetic fibres. These polymers are elastic, very strong and resist UV light degradation. Explain why cotton (once used to make climbing ropes) is no longer used ? PLTS Creative thinkers Reflective learners Team workers Effective participators Self managers Independent enquirers Numeracy: In a polymer there may be up to 3000 molecules all bonded together to form very long chains that behave like fibres. Cellulose found in cotton, linen and wood is the most common polymer. Literacy: Materials, compounds, physical properties, man – made, synthetic, polymers, monomers, plastic, natural, cotton, silk, wool, hair, nylon, polythene, polyester and fibre We will focus on exploring issues, events or problems from different perspectives
  9. 9. C2.2 Polymers everywhere Decide whether the following statements are true or false: Introduction: Plastics like polythene, polypropylene, polycarbonate glass and neoprene are all made from polymer fibres. These polymers have been designed to be used in many different types of products from the simple plastic bag to wet suits to a replacement for glass. Avoiding plastic in everyday life is very difficult because it is so cheap to manufacture. Extension questions: 1: Give five examples of how a) plastics like polythene and b) fibres like nylon are used in every day products ? 2: Explain why a) bus shelters now use polycarbonate plastic rather than glass and b) why roles are made from nylon rather than plant fibres ? 3: Give two uses for a) kevlar, b) nylon c) PVC and d) polythene ? 4: Up to 20% of the cost of foods is due to the plastic used in its packaging discuss whether this is a good use of plastic ? Know this: a: Know that synthetic polymers are made to suit their intended use. b: Know that synthetic polymers are made from very long chains of repeating monomers. Friday 21 October 2011
  10. 10. Key concepts Look at the photograph and information and answer all the questions: Explain why man made plastic have become so important in modern day life ? Give five examples of a) short lived plastic item, for example the plastic bag and b) long lived plastic item for example a plastic toy ? C2.2 a Plastics and polymers Polymers are long chain giant organic molecules are assembled from many smaller molecules called monomers . Another common name for many synthetic polymers is plastic which comes from the Greek word &quot;plastikos” used for moulding or shaping. Many objects in daily use from packing, wrapping, and building materials include half of all polymers synthesized. Other uses include textiles, TV's, CD's, automobiles.
  11. 11. C2.2 b Look at the photograph and information and answer all the questions: The word polymer literally means &quot;many parts.&quot; A polymer contains many units or monomers which are joined together to form a long chain. Polymers can be man made or naturally occurring like cotton, silk or even human hair. Three of the best know polymers used widely are nylon, rubber and polythene. Except rubber, these are synthetic polymers made in factories. Give two uses of the following polymers a) polythene b) cotton c) plastic d) Nylon and e) polystyrene ? PVC a synthetic polymer is used to make window and door frames...give three advantages to using PVC when compared to using natural materials like wood ? Plastics have a very short life cycle and normally disposed of after one use. Plastic no biodegrade and can fill landfill. Why is this a problem for us of ? Products that use synthetic polymers Neoprene Kevlar Latex PET polythene HD PVC LD PVC Key concepts
  12. 12. C2.3 Plenary Lesson summary: polythene chained polymers fibres Friday 21 October 2011 Plastics and synthetics polymers like nylon, lycra, neoprene and polyesters are everywhere. There are much strong and more durable than there natural counter part. These fibres are very strong because of the bonding between the monomers and the fibres themselves. How Science Works: Research into tensile strength and how they test the tensile strength of fibres like nylon and cotton. Preparing for the next lesson: Synthetic ________ like PVC, ____________, polyester, neoprene and polypropylene are made form long ________ molecules that behave like, ________. These can then be used to make very string, light and durable high tech materials. Decide whether the following statements are true or false : False True 3: Transparent polycarbonate plastic is often used instead of glass ? False True 2: Polythene is made form lots of ethene molecules joined together in a chain? False True 1: PVC stands for poly vinyl chloride ?
  13. 13. C2.3 Testing times Decide whether the following statements are true or false: <ul><li>Lesson objectives: </li></ul><ul><li>Understand how to use the correct words to describe the properties of a material </li></ul><ul><li>Understand how to test materials for their strength, quality, durability and safety </li></ul>We will focus on. Friday 21 October 2011 First activity: Explain why body armour kits used by both the police and the military are made using kevlar panels (carbon fibre) PLTS Creative thinkers Reflective learners Team workers Effective participators Self managers Independent enquirers Numeracy: Testing the ‘tensile strength’ of a fibres like nylon or cotton is simple. Place successively larges masses and determine its breaking point. Literacy: Materials, compounds, physical properties, quality, tensile strength, elasticity, synthetic, polymers, monomers, plastic, natural, nylon, polythene, polyester and fibres. We will focus on planning and carrying out research, appreciating the consequences of decisions
  14. 14. C2.3 Testing times Decide whether the following statements are true or false: Introduction: Modern materials sometimes need to be strong. Materials like steel and nylon have a very high tensile strength even when stretched. Materials with high tensile strength, even when stretched can be used because they will perform well even when under loading. Tensile strength measure the amount of force required to break a material like a rope or steel fibre. Extension questions: 1: Why do a) ropes have to be elastic and strong b) polythene bags have to be strong and cheap c) carbon fibre has to be light and strong d) PET plastic has to be strong and non absorbent ? 2: Although carbon fibre gram for gram is stronger than steel, why is it not in the manufacture of the average family car ? 3: Give three properties of a material that would be ideal suited to make a climbing rope ? 4: How would you expect the tensile strength of cotton and nylon to differ ? Know this: a: Know that the properties of a material determine its use by material scientists. b: Know that tensile strength can be tested by determining the load required to break that material. Friday 21 October 2011
  15. 15. Key concepts Look at the photograph and information and answer all the questions: Make a table and compare the properties of each material i.e. carbon fibre, wood and aluminium metal ? Explain why modern tennis racquets are made from carbon fibre ? When designing, testing and making a tennis racquet designers and material scientists will choose the best material for each part of the tennis racquet. The racquet frame: Three possible material have been used in the manufacture of a tennis racquet, wood metal and graphite (carbon fibre) C2.3 a Choosing the right material Carbon fibre Wood Aluminium metal
  16. 16. Key concepts Look at the photograph and information and answer all the questions: C2.3 b Choosing the right material When designing, testing and making a tennis racquet designers and material scientists will choose the best material for each part of the tennis racquet. The racquet string: Three possible materials have been used in the manufacture of a tennis racquet, cat gut, polyester and nylon string Make a table and compare the properties of each material i.e. cat gut, polyester string and aluminium string ? Explain why modern tennis racquets are made using nylon string ? Cat gut Polyester string Nylon string
  17. 17. C2.3 c Look at the photograph and information and answer all the questions: If you're a climber then you will entrust your life to a material scientists who has determined that the rope that you are using has sufficient tensile strength not to break if you fall. Tensile strength measures the force required to pull something such as rope or wire to the point where it breaks. The tensile strength of a material is the maximum amount of tensile stress that it can be subjected to before failure. Why is a very high tensile strength important for all climbing ropes ? Why do materials scientists build in a certain amount of ‘elasticity’ into the fibres that make climbing ropes ? Explain why you should replace your climbing rope after a serious fall ? Key concepts
  18. 18. C2.3 Plenary Lesson summary: mass tensile fair material Friday 21 October 2011 Spider’s silk gram for gram is about 20 times stronger than steel. The problem is that no scientists has successfully taken the gene from a spider and put it into a cotton plant. If you could you would be very rich and have super strong cotton (stronger than steel) How Science Works: Research into how fibres like cotton, wool and silk have ideal properties to make woven cloth. Preparing for the next lesson: _________ strength of any ________ tells us how strong a material is. To make a comparison between one material and another, an equal _______ or quantity needs to be used to make it a ______ test. Decide whether the following statements are true or false : False True 3: Steel’s tensile strength is higher than pig iron which is very brittle ? False True 2: Tensile strength is measure in newtons ? False True 1: Nylon has a very low tensile strength when compared to cotton or linen ?
  19. 19. C2.4 Zooming in on cloth Decide whether the following statements are true or false: <ul><li>Lesson objectives: </li></ul><ul><li>Understand the general properties of natural and man made fibres </li></ul><ul><li>Understand how atoms and molecules behave in long chains </li></ul><ul><li>Understand how to model molecules </li></ul>We will focus on. Friday 21 October 2011 First activity: Compare cloth made form wool and cotton fibres behave differently ? PLTS Creative thinkers Reflective learners Team workers Effective participators Self managers Independent enquirers Numeracy: To understand why cloth behaves the way it does we have to use a microscope and lenses that can magnify up to 1000 times. At this magnification we can see how the fibres behave in the weave. Literacy: Polymers, long chains, monomers, fibres, materials, compounds, physical properties, quality, tensile strength, elasticity, synthetic, plastic, natural, nylon, polythene and polyester a We will focus on supporting conclusions using reasoned arguments and evidence
  20. 20. Decide whether the following statements are true or false: Introduction: Woven cloth made form natural or synthetic fibres like cotton and polyester behave as a result of the properties of the individual fibres they are made from. How each cloth behaves is determined by how the molecules that make up each fibre behave. Silk fibres are microscopically smooth and narrow so that the fibres can slide across one another, where as wool fibres are microscopically rough and large. Extension questions: 1: Explain why most children do not like have wool products against their skin ? 2: Put the following in order of size (smallest first) monomer, fibre, polymer, atoms ? 3: Explain why silk sheets are very popular and considered a luxury product ? 4: Explain why wool garments are able to keep you warm ? 5: Explain why wool clothing is useless in wet conditions ? Know this: a: Know how to describe the properties man made and natural fibres. b: Know how to model molecules found in polymers that make up fibres. Friday 21 October 2011 C2.4 Zooming in on cloth
  21. 21. Key concepts Look at the photograph and information and answer all the questions: Cotton is not made; it is a plant which grows in warmer parts of the world. Cotton plants have yellowish pink flowers which bloom very briefly. The seed bearing part of the plant is known as the boll and it is this which is picked to make cotton. For thousands of years cotton has been harvested, cleaned, spun, woven, bleached and dyed to make an astonishing variety of different items. C2.4 a Making cotton a natural polymer If you looked at a) silk and b) cotton cloth under the microscope, how would the fibres differ to the wool fibres pictured here ? If you looked at a) silk and b) cotton cloth under the microscope, how would the fibres differ to the wool fibres pictured here ? Finished product....cotton Spinning cotton Harvesting cotton
  22. 22. Key concepts Look at the photograph and information and answer all the questions: C2.4 b Zooming in on polymers Cotton yarn or fibres can be made into cloth by weaving but weaving. Threads run lengthways from back to front of the loom. These are known as the &quot;warp&quot;. Using a shuttle yarn is threaded widthways - this is the &quot;weft&quot;. The properties of the cotton cloth depends on the interaction of the criss-crossing fibres and the tensile strength of the individual cotton fibres. Look at the picture above left. Explain the how the fibres interact with one another in this woven wool fabric ? Wool fibres are rough and relatively thick. Explain how these properties helps wool to be a good insulator ? Zoom x 10 Zoom x 100 proposed structure of polymer chain
  23. 23. C2.4 Plenary Lesson summary: between synthetic monomers model Friday 21 October 2011 Atoms are incredibly small measuring fractions of a nanometre in diameter. No one really knows what single atoms look like, but if we look at long chained molecules we can begin to model what they are like and their properties. How Science Works: Research into the discovery of synthetic fibres like nylon, neoprene, lycra and polythene Preparing for the next lesson: The properties of cloth made from man-made or ________ fibres depends on the ___________ that the long chains are made from and the interaction __________ many fibres. To understand and ______ how these fibres behave we have to think in terms of the atoms they are made from. Decide whether the following statements are true or false : False True 3: Cloth is made by weaving in different directions natural and synthetic fibres ? False True 2: A polymer molecule is approximately 1000 to 10,000 nanometres in size ? False True 1: Silk and wool are both synthetic fibres ?
  24. 24. C2.5 The big new idea Decide whether the following statements are true or false: <ul><li>Lesson objectives: </li></ul><ul><li>Understand how synthetic polymers like nylon and lycra were first discovered </li></ul><ul><li>Understand that polymers are long chained molecules made from many monomers chemical bonded together </li></ul>We will focus on. Friday 21 October 2011 First activity: Give five uses of polythene which is made form joined thousands of ethene gas molecules together under high pressure using a catalyst ? PLTS Creative thinkers Reflective learners Team workers Effective participators Self managers Independent enquirers Numeracy: In 1933, two chemists (Fawcett and Gibson) made polythene from joining many thousands of ethene molecules together. The age of plastic bags and plastic packaging was born ! Literacy: Polymers, long chains, monomers, fibres, physical properties, quality, tensile strength, elasticity, synthetic, plastic, natural, nylon, polythene and polyester. We will focus on explore issues, events or problems from different perspectives
  25. 25. C2.5 The big new idea Decide whether the following statements are true or false: Introduction: A chemist named Wallace Carothers first discovered how to manufacture two very important polymers Nylon and Neoprene. Nylon was used as an alternative to silk and cotton and neoprene was used as an insulating material found in diver’s wetsuits. Both nylon and neoprene polymers were made by forcing many thousands small molecules to join one another under very high pressure. Extension questions: 1: Name two products made from a) nylon and b) neoprene ? 2: In 1934 The USA and Japan were not trading commodities like silk, how did this led to the discovery of the nylon replacement ? 3: Polythene is made by joining thousands of ethene molecules together. Where does ethene gas come from ? 4: Give three uses of polythene apart form the making plastic bags ? 5: Give three ‘pros’ and three ‘cons’ when using plastics ? Know this: a: Know how synthetic polymers were first discovered. b: Know that polymers are long chained molecules. Friday 21 October 2011
  26. 26. C2.5 a Look at the photograph and information and answer all the questions: The word polymer literally means &quot;many parts.&quot; A polymer contains many units or monomers which are joined together to form a long chain. Polymers can be man made or naturally occurring like cotton, silk or even human hair. Three of the best know polymers used widely are nylon, rubber and polythene. Except rubber, these are synthetic polymers made in factories. Give two uses of the following polymers a) polythene b) cotton c) plastic d) Nylon and e) polystyrene ? PVC a synthetic polymer is used to make window and door frames...give three advantages to using PVC when compared to using natural materials like wood ? Plastics have a very short life cycle and normally disposed of after one use. Plastic no biodegrade and can fill landfill. Why is this a problem for us of ? Ethene Ethene Ethene Ethene Poly(ethene) Making polythene form ethene Products made form polythene Key concepts
  27. 27. Key concepts Look at the photograph and information and answer all the questions: Compare the properties of PET (1) plastics and LDPE (4) plastics ? If I want to sell a liquid product in small and very large bottle which plastic types might I choose and why ? Packaging plastics are produced in chemical factories and have rather long names. There are seven major groups. The first four are listed below: PET: polyester (polyethylene terephthalate) HDPE: high density polyethylene PVC: polyvinylchloride LDPE: low density polyethylene C2.5 b Different types of plastics
  28. 28. Key concepts Look at the photograph and information and answer all the questions: C2.5 c The plastics raw materials (called polymers) usually come in granule or powder form. They are then converted using heat and pressure on special processing machinery to produce bottles, tubs, films, crates, etc. PP: polypropylene PS: polystyrene Other: Any other plastic that fall outside of 1 to 6 Different types of plastics Compare the properties of PP (5) plastics and PS (5) plastics ? Explain why short lived plastic like shopping bags, food trays and plastic drinks bottles are very environmentally unfriendly ?
  29. 29. C2.5 Plenary Lesson summary: materials monomers chains fibres Friday 21 October 2011 Nylon, polyester, lycra, and neoprene all synthetic fibres which reduce the demand for natural fibres including wool, silk, cotton and linen. Suddenly the supply of fibres were not in the hands of farmers but chemists who mass produced them more cheaply and often with better properties. How Science Works: Research into how changing the length of the polymer chain can alter the physical properties of the synthetic fibres that we make. Preparing for the next lesson: Polymers are made form many thousands of ________ joined together to form long ________ that behave like _______. These fibres can then be made into cloth, rope or other useful ___________. Decide whether the following statements are true or false : False True 3: Many synthetic polymers we now use were first discovered during the 30s ? False True 2: Polythene is made form many vinyl chloride monomers joining together ? False True 1: Nylon was a replacement for silk and natural polymer ?
  30. 30. C2.6 Molecules big and small Decide whether the following statements are true or false: <ul><li>Lesson objectives: </li></ul><ul><li>Understand the difference between long and short chained polymers </li></ul><ul><li>Understand that crystalline polymers are more dense and therefore stronger than non crystalline polymers </li></ul>We will focus on. Friday 21 October 2011 First activity: Difference in boiling points are used to separate out the different fraction found in crude oil. How does boiling point change according to the size of the molecules found in fuels like methane, butane, octane and paraffin. PLTS Creative thinkers Reflective learners Team workers Effective participators Self managers Independent enquirers Numeracy: In candle wax the polymer chains are between 20 to 30 carbon atoms long. In polythene, the chains are between 5000 to 10,0000 carbon atoms long ! Literacy: Polymers, long chains, short chains, monomers, fibres, physical properties, quality, tensile strength, elasticity, synthetic, plastic, natural, nylon, polythene and polyester. We will focus on plan and carry out research, appreciating the consequences of decisions
  31. 31. C2.6 Molecules big and small Decide whether the following statements are true or false: Introduction: Polymers can be made from short, long chains and even chains with branching. The length of the molecules which make up a polymer or the presence of branching can affect the physical properties of a polymer like nylon, polythene, neoprene, PVC and polyester. High density polythene which is strong is made from long chains with no branching. Low density polythene which is less soft and commonly used to make children's toys is made form short branched chains. Extension questions: 1: Give three examples of products made with a) high density (hard) plastics and b) low density (soft) Plastics ? 2: Explain why young children's toys are made with low density soft plastics ? 3: Explain how by adding branches to polymer chains this can reduce the density of a plastic ? 4: Low density plastics start to soft in boiling water…explain why products made from these plastics are not dishwasher proof ? Know this: a: Know that the length of chains affects the properties of polymers like nylon, polythene and neoprene. b: Know that stronger and more dense plastic are made from longer chained polymers. Friday 21 October 2011
  32. 32. C2.6 a Look at the photograph and information and answer all the questions: <ul><li>The properties of any polymer are determined by three things. </li></ul><ul><li>The atoms that they contain </li></ul><ul><li>The length of their chains </li></ul><ul><li>How the fibres interact with one another </li></ul><ul><li>Scientists can now change properties like strength, elasticity and density by changing the atoms inside the polymer chains. </li></ul>In wax, the polymer chains are only 20 to 30 carbon atoms long. Explain why wax is both soft and brittle ? In PET plastic which is used to make drinks containers, the fibres line up end to end allowing high density plastic. Why is this an ideal property for a drinks container ? Spider’s silk a natural polymer which gram for gram is stronger than steel. What you expect the fibres to resemble those from wax or PET plastics ? HDPE High and low density polymers LDPE PET Wax Key concepts
  33. 33. Key concepts Look at the photograph and information and answer all the questions: Compare the physical properties of HDPE and LDPE ? Explain why pallets and crates are made form HDPE and not LDPE? High density polyethylene (HDPE) is the third largest commodity thermoplastic. A major outlet for HDPE is in blow-moulding applications such as bottles, packaging containers, drums, fuel tanks for automobiles, toys and house wares. Injection-moulded articles made from HDPE include crates, pallets, packaging containers and caps, paint cans, house wares and toys. C2.6 b Different types of plastics
  34. 34. Key concepts Look at the photograph and information and answer all the questions: LDPE is the low density version of PE. This has less hardness, stiffness and strength compared to HDPE, but better ductility. It is opaque and only thin foils can be transparent. LDPE is used for packaging like foils, trays and plastic bags both for food and non-food purposes. Used as protective coating on paper, textiles and other plastics, for instance in milk cartons C2.6 b Different types of plastics Compare the physical properties of HDPE and LDPE ? Explain why bin liners and cling film are made form LDPE and not HDPE?
  35. 35. C2.6 Plenary Lesson summary: closely short branches long Friday 21 October 2011 High density plastic is not very easily degraded once placed in landfill. It take many thousands of years to rot away. Its disposal by incineration is also problematic because when burnt it can produce very toxic emissions which contain small quantities of Arsenic and other toxic compounds How Science Works: Research into how scientists can change the properties of plastics by introducing cross linking and plasticizers Preparing for the next lesson: Low density plastic (LDPE) are made form ____ chains and also have some _______ added to the polymers. High density plastics (HDPE) are made from ______ chains and which allow the polymer chains to pack ________ together. Decide whether the following statements are true or false : False True 3: The longer the polymer chains, the higher the density of the plastic ? False True 2: Polythene packaging is made from LDPE ? False True 1: Plastic plates, cups and bowls are made form HDPE ?

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