TOPIC 3 - U1 - Materials Flashcards
2 Types of materials
Natural materials
Synthetic materials
Def : Natural materials
Naturally occuring materials found in nature
Def: Synthetic materials
Artificial or man-made materials from different chemicals added together
Natural or Synthetic?
wood
metals
concrete
glass
plastic
ceramic
wood - N
metals - N
concrete - S
glass - S
plastic - S
ceramic - S
Fibres classified as
Natural / synthetic
3 Natural plant fibres
cotton, flax, sisal
2 Natural animal fibres
wool, mohair
Uses for natural fibres
used to spin into threads that are then woven or knit into textiles
Uses for synthetic fibres
can be produced from which textiles can be woven or knitted
3 Synthetic fibres
polyester, nylon, terylene
How are composite materials made
by mixing 2 substances together like grass and dung, where grass is the reinforcement + dung is the matrix
Explain reinforced concrete in context to composite materials
concrete is the matrix + steel bars are the reinforcement
Explain fiberglass in context to composite materials
the tiny shards of glass are the reinforcement + they are held together by resin, the matrix
Explain wood in context to composite materials
natural composite materials have cellulose fibres that are held together by lignin
What type of bonds keep metals together and explain how metals are bonded
- They are held strongly together by metallic bonds.
- Metal atoms in a crystal have outer electrons that can move around freely between atoms. metals are made of rows of positive ions surrounded by a sea of moving electrons which are strongly attracted by positive ions.
What type of bonding takes place between concrete
It has both ionic and covalent bonding
What is concrete made from
a mixture of sand, gravel, cement and water
Where does the long thin crystals that overlap in concrete come from and what is that material made of
it comes from the cement that’s part of the concrete.
cement is made of a mixture of calcium silicate and aluminium silicate
Why does concrete shatter easily when hit with a hammer
Because the crystals in the concrete are ionically bonded and the sand is covalently bonded.
How is glass made
by heating calcium carbonate with sodium carbonate and sand. they then melt together and forms liquid glass. it’s then cooled to form solid glass
What is glass made of
non-crystalline solids
Why is glass considered a liquid
it has a structure of a liquid, but behaves like a solid
What type of bond holds glass together
covalent bonds which forms a giant covalent structue
Def:
Giant covalent structures
when atoms form covalent bonds with neighboring atoms to create giant lattices
What is a polymer
a large molecule made up of chains of repeating units of monomers
2 Types of polymers
natural polymer - cellulose
synthetic polymer - plastic
Cellulose is a natural polymer in wood. Explain the structure of cellulose
It’s a complicated structure containing atoms of C, H and O2. They are strong due to their electrostatic forces and covalent bonds. It cannot be stretched or broken, but can be bent. Held tightly together
How is cellulose fiber made and what is its use
made when wood is crushed and it forms long thin pieces which is then used to manufacture paper
What is plastic made of
fossil fuel sources like crude oil and natural gas
How is plastic formed
from long chains of carbon atoms, together with other elements that are held together by strong covalent bonds
Why is plastic a source of pollution
because it cannot decompose is the environment
4 Types of plastic
polythene
nylon
melamine
polyurethane
Why is it difficult to break polythene
molecules are held together strongly and molecules are lined in different directions which makes them flexable
What is the use for polythene
to make shopping bags
Why is nylon a strong material
The forces between the molecules are electrostatic. The molecules can slide next to each other making nylon very flexible
What is nylon used for
making clothes, fishing lines and ropes
What type of bond is between melamine molecules
covalent bonds between polymer
Describe melamine
its very hard and rigid. melamine doesn’t break or melt easily
What is melamine used for
making plastic surfaces for desks + manufacture plates and bowls
How is polyurethane bonded together
joined together very loosely in a random way
Describe polyurethane
plastic can be squashed or stretched without permanently changing its shape. It has weak forces and is not very strong. weak plastic
What is polyurethane uses
to make foam mattresses
