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Polymers- Chemistry

msreenandini English 43 cards

Cards in this deck (43)

  1. 1Materials are chosen for specific jobs because of their propertiesBefore 1900, everything was made from naturally occurring items, because then, people didn't know how to change properties of materials
  2. 2Why chocolate is bad for shoes: -cracks -melts -attracts animals -wears away -messy floorLatex is a natural polymer that comes from rubber trees, that can be treated to be made into several products
  3. 3South American Indians dipped their feet into liquid latex, forming the first 'wellies'Why latex is good for shoes:
    -flexible
    -hard wearing
    -waterproof
    -elastic
    -solid at room temp
    -tough
  4. 4A polymer is a molecule with a very long chain of atomsSome natural polymers:
    -cotton
    -leather
    -wool
  5. 5Some synthetic polymers: -polythene -neoprene -nylonCotton has been used for many years, to make fabrics. It grows around cotton seeds
  6. 6Silk is used for high quality clothing. It is a protein fibre from silkworm cocoonsWool is a good insulator. It is a protein fibre from sheep
  7. 7Synthetic polymers can be superior to natural polymersWood can be replaced with plastics, as they are lighter and do not rot
  8. 8Paper bags can be replaced by plastics, as they are lighter and waterproofUses of synthetic polymers:
    - Food containers
    -Prosthetic body parts
    -Soldiers' helmets
    -Wet suits
    -Sails
  9. 9Uses of natural polymers: -Clothing -Rubber cloves -Paper -FabricsSTRONG: Materials that take a large force to break. The force that breaks the material tells you its strength
  10. 10TENSION: Materials that are strong when stretched, are strong in tensionCOMPRESSION: Materials that can take a lot of weight, are strong in compression
  11. 11STIFF: Materials that are difficult to stretch or bendHARD/SOFT: Materials that can scratch a softer one/ materials that can be scratched
  12. 12DENSITY: How heavy a material is for its volumeACCURACY: How close a measurement is to the true value
  13. 13When materials are tested, the are repeatable, and reproducibleAll factors need to be taken into account when testing for materials. eg. temperature
  14. 14Properties of materials depend on their makeup- stitches, weaves, fibres, molecules, atomsFeatures visible with the naked eye are macroscopic features
  15. 15Features visible only with a microscope are microscopic features-1millimetre is a thousandth of a metre
    -1 micrometre is a millionth of a metre
    -1 nanometre is a billionth of a metre
  16. 16Atoms and molecules are measured in nanometresIn 1933, two scientists discovered polythene. Their container of ethene had a leak, so they added more ethene. They found a waxy substance 2 days later. The ethene molecules had joined together to form long chains, with the help of the oxygen from the air into the hole acting as a catalyst
  17. 17Polymers are made of singe molecules called monomersPOLYMERISATION: Small molecules joining up into long chains
  18. 18Wallace Carothers left a mixture of chemicals in a jar for 5 weeks. He found a rubbery solid, which he developed into neoprene. In 1934, his team came up with nylonBonds between atoms are strong, so molecules do not break
  19. 19Forces between molecule chains can be weak or strong. Stronger forces means the material is tougher. The molecules are hard to separate. Weaker forces means the material is less tough. The molecules are easy to separateMolecules with strong forces between them have higher melting points, as they require more energy to separate from each other
  20. 20VULCANISATION: Mixing polymers with sulphurs and heating them to produce tougher, more durable materialsVulcanisation was discovered by Charles Goodyear, in 1840. He mixed sulphur and rubber, and accidentally dropped some on a hot stove, and found later on that it had hardened
  21. 21The polymer molecule chains make cross links with the sulphur atoms, stopping them from sliding, making the material strongerpoo
  22. 22poo 2Prosthetic body parts are made of polypropylene
  23. 23PET is used to make disposable drink and food containersWetsuits are made of neoprene as they are thick which keeps in body heat
  24. 24PVC is used to make window frames, so it has to be durable and hardPVC is also good for clothing, but it needs to be made softer using a plasticiser
  25. 25PLASTICISER: An oily liquid with small molecules that sit between the polymer chains, holding the chains apart, weakening the forces of attraction, allowing the chains to slide easier, and is therefore a softer, more flexible materialCling film is made of plasticised PVC
  26. 26CRYSTALLINE: Polymer chains arranged in neat linesPolythene made under high pressure forms branches on the polymer chains, making the material less dense and more flexible
  27. 27Polythene made using metal compounds as a catalyst, speeding up the rate at which the ethene molecules join together, are neat and crystalline, making the material more dense and strongLDPE: Low density polythene with branched polymer chains
  28. 28HDPE: High density polythene with crystalline polymer chainsGore-tex is a waterproof material, that is a sandwich of two pieces of clothe and PTFE in between, which has tiny holes that will allow sweat to go out, but aren't big enough for water molecules to fit through
  29. 29Kevlar was originally a polymer that was dissolved in high concentrations of sulphuric acid to make it liquid, then put through a tiny hole to obtain fibresMonomers come from crude oil
  30. 30CRUDE OIL: thick, sticky liquid formed over millions of years by plankton remainsCrude oil is made up of different sized hydrocarbons, so it is useless on its own- the hydrocarbons need to be separated into groups of similar sizes
  31. 31Crude oil is heated in a furnace, and the hydrocarbons separate by their different boiling points. Smaller hydrocarbons are at the top of the fractioning tower, larger at the bottom, as it is cooler at the top and hotter at the bottomPetroleum gas is made from hydrocarbons boiled below 0 degrees. It is used for bottled gas
  32. 32Petrol is made from hydrocarbons boiled at 70 degrees. It is used for petrol in vehiclesNaphtha is made from hydrocarbons boiled at 140 degrees. It is used for chemicals
  33. 33Kerosene is made from hydrocarbons boiled at 190 degrees. It is used for jet fuelLight gas oil is made from hydrocarbons boiled at 270 degrees. It is used for diesel for vehicles
  34. 34Heavy gas oil is made from hydrocarbons boiled at 320 degrees. It is used for central heating fuelLubricating oil is made from hydrocarbons boiled at 350 degrees. It is used for lubricants
  35. 35Bitumen is made from hydrocarbons boiled above 350 degrees. It is used for roads and roofingSome larger molecules are broken up and used in chemical synthesis - only 4% of crude oil is used for this
  36. 36Chemical synthesis is a way of producing new, synthetic materials such as polymersNANOTECHNOLOGY: the use and control of nanoparticles
  37. 37Total surface is area is larger for smaller particlesGecko's feet have millions of tiny nanometre size hairs, which give it a huge surface area and provide the stickiness required to stay on walls
  38. 38Materials containing nanoparticles are often highly reactive or have unusual propertiesActicoat is a bandage containing silver nanoparticles, that dissolver very quickly when moistened, so blood will allow it to work fast
  39. 39Nanoparticles are in nature too: -salt particles in the air from waves help rain and snow to form -proteins controlling biological systems - teeth enamelSunscreen uses zinc oxide or titanium oxide nanoparticles that can be absorbed by the skin, to reduce the visible, creamy, white look of the product
  40. 40Tennis balls have an extra layer of 1nm size clay particles mixed with rubber, keeping them inflated for longerNanoparticles added into carbon fibres make them lighter and stronger, such as tennis rackets
  41. 41Nanoparticles were used to make a flexible display, which retains images after it is turned off- this could replace posters and electric signs, saving energy and paperClothing with zinc oxide nanoparticles give better UV protection
  42. 42Stain resistant clothing have tiny nanoscale hairs that repel water and other materials. This can reduce the energy and water used in washing clothesWindows coating in nanoparticles can clean the window themselves- when it accesses any light, it breaks down any dirt on the glass
  43. 43Some doctors are concerned that nanoparticles are so small they will be able to enter our brain through the bloodstream, meaning any normally harmless chemicals could be highly toxic at nanoscale

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Flashcards on Polymers- Chemistry , created by msreenandini on 28/12/2015.
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