C2 - Material choices Flashcards
What is crude oil?
A mixture of hydrocarbons.
What is fractional distillation?
Takes place in a fractioning column separated into different fractions. Crude oil is sent through the bottom of the column (the hottest part) and Slowly makes it’s way to the top (coolest part) leaving different parts of the crude oil in each fraction as it goes.
Fractional distillation Separates crude oil into different parts. Give examples of products that condense in the top half. what the are used for?
Gasoline - used in cars
Kerosene - aircraft fuel
Fractional distillation Separates crude oil into different parts. Give examples of products that condense in the bottom what the are used for?
Diesel - cars, lorries, busses
Fuel oil - ships
Bitumen - roads and roofs
What is methane?
An natural gas. Used in cookers, domestic burners, Bunsen burners and some power stations
What are the properties of polymer chains?
Long molecules that lie side by side.
Can uncoil and slide past each other. This makes the material flexible.
If you make the molecules of a polymer longer what will happen?
Stronger forces of attraction
Stronger, less flexible material is produced
What is the name for adding molecules to polymers during manufacture?
Plasticising
What do plasticisers do to a material?
They push the polymer molecules apart weakening the forces between them.
= softer flexible material.
What are the characteristics of PVC and uPVC. What are some uses?
PVC = hard
Used for pipes and window frames
uPVC = soft
Used for clothing and flooring
Chemical bonds can be formed to lol together the chains of some polymers. What is this called?
Cross linking
What are the characteristics of materials with cross links.
Tougher material. Less flexible.
What is a polymer?
Large molecule formed from many smaller molecules (monomer)
Characteristics of low density polyethene.
Structure is not crystalline.
Low density = force of attraction is weaker.
Low melting point.
Less strong.
Does HDPE or LDPE have a crystalline stricture.
High density polyethene.
