Materials And Nanoparticles Flashcards
What are the properties of ceramics?
Chemically unreactive Hard Stiff Brittle Change very little when heated Have giant structures
How are clay ceramics made?
Made from clay mounded into a shape and heated to a high temperature
E.g. brick, porcelain and China
How do you make Glass?
Made from melting sand
Atoms aren’t arranged in a regular way to form crystals, so glass is transparent
What are the properties of polymers?
Strong and chemically unreactive
Poor electrical and thermal conductors
Made softer and more flexible by adding plasticisers
What are the properties of metals?
Most are string, hard, shiny (lustrous) and high melting points
Malleable
Good electrical and thermal conductors
What are composite materials?
A mixture of two or more materials to make a new material with improved properties
Indivisible materials can often be separated from each other using physical separation techniques
How do you make concrete?
Made from mixing cement, sand, aggregate(small stones) and water
The sand and aggregate form the reinforcement for the concrete
Reinforcement is bonded together by cement which forms a matrix
What are properties of steel reinforced concrete?
Easily squashed
Making it strong in compression and tension
Less dense and cheaper than steel
What is pycrete?
Pycrete is a mixture of ice and sawdust
It is half as strong as concrete but much lighter
What is fibre glass?
Thin glass fibres are reinforced
Brittle and have low density
High tensile strength = hard to stretch
Polymer resin is in the matrix so it is hard wearing but not strong
Lightweight but strong and tough material
What are laminates?
Wood is its natural composite
Stringer with the grain than across the grain
Plywood is made of an odd number of sheet glued at right angles to each other
How are nanoparticles useful in sunscreen?
Nanoparticles don’t break down in the sun
Usually uses titanium which offers a good protection from UV rays.
Titanium is stable in sunlight so they reflect/absorb the UV rays.
Looks white because nanoparticles absorb visible light
They scatter visible light to create transparency and decrease concentration.
How are nanoparticles useful in silver?
Break down membrane of bacteria which kills it
What are the problems with nano particles?
Small enough to be breathed in
Small enough to pass through cell membranes
Large surface area to volume ratio, allows them to catalyse harmful reactions.
