C2- material choices
- Created by: willbrewin1
- Created on: 18-04-15 11:26
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- C2- material choices
- all materials are made up of chemicals (groups of atoms bonded together
- Natural
- wood, paper, cotton (plants). wool, silk etc (animals)
- Natural
- material properties
- melting point- most pure chemicals have unique. solid goes to liquid
- stiffness- force taken to bend a material
- hardness- how difficult to cut into
- density- how much mass in a specified volume
- strength- how good a material is at resisting a force (can be flexible and strong)
- possible uses
- plastics- hard, stiff and low density
- rubber- strong but soft and flexible eg car tyres
- nylon- soft, flexible, high tensile strength eg rope
- properties depend on the materials its made from- suitability should be assessed
- crude oil- mixture of hydrocarbons- when heated smaller chain molecules split from rest and longer chain molecules stay together- fractional distilation- refining
- Hydrocarbons- strong covalent bonds between atoms, weak intermolecular forces
- POLYMERS
- polymerisation is where high pressure is used to joing small chained molecules to make longer molecules- eg inn milk cartons
- this means you can change molecular chain length to get different properties- thats why plastics have different properties
- forces between polymer chains determine polymer strength
- weak forces- slide over each other, low melting point and easy to stretch
- strong forces- dont slide over each other and so high melting point and more rigid
- polymer modififcation
- change chain lenght- longer means more rigid and higher melting point
- crosslinks- chemically bond chains together, stronger and higher melting point
- plasticisers- reduces friction between chains, softer and easier to shape.
- make more crystaline- straight chains with no branches, fit closer, higher density, higher melting point
- nanotechnolo-gy is a branch of technology dealing with the making and use of nano particles
- can occur naturally- combustion (particulates) and sea spray
- have different properties to their regular sized counterparts
- silver- anti-bac properties. also some can be added to sports equipment to strengthen without adding weight
- dont know long term effects- must be clearly labelled on producst
- all materials are made up of chemicals (groups of atoms bonded together
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