Polymers

Question 1

What are synthetic plastics manufactured from

Answer 1

Crude oil

Question 2

How are plastics made from carbon polymers

Answer 2

Adding various additives

Question 3

What are some ways to form plastic into different shapes

Answer 3

injection moulding, compression moulding and extrusion

Question 4

What was and when was the first plastic made and what type of plastic was it

Answer 4

Bakelite 1907, thermosetting plastic

Question 5

What is the percentages of different groups of hydrocarbons in crude oil

Answer 5

aliphatics (25%), aromatics (17%) and naphthenes/
cycloalkanes (50%)

Question 6

What non hydrocarbon groups does crude oil contain

Answer 6

sulphur, nitrogen, oxygen and metallics

Question 7

Why do isoalkanes have a lower boiling point than normal alkanes

Answer 7

isoalkanes ,which are branched, increase the distance between two neighbouring alkane groups and decreases the surface area in which the two groups can interact so the intermolecular forces are weaker, meaning less energy is required to separate these molecules

Question 8

What percentage of crude oil is used for plastic manufacture

Answer 8

2.7%

Question 9

What are thermoplastics and describe its bonding + structure

Answer 9

Plastics that soften when heated and will set when cooled. This can be repeated, in a process of reheating and remoulding. Formed from polymers held together by weak IMFs.

Question 10

What are thermosetting plastics

Answer 10

Plastics that set when first cooled down but will not soften when reheated. Therefore cannot be remoulded and will burn when too much heat is applied. Formed from polymers with covalent bonds between them

Question 11

What gives plastics their plasticity

Answer 11

The fact that the polymers can move over each other when a load is applied. (no dislocations like in metals)

Question 12

What are copolymers and what are the four types

Answer 12

Polymers made from more than one monomer - random, alternating, block (consists of sections containing one type of monomer), graft (contains monomer sections that are attached to a chain of a different monomer)

Question 13

General properties of polymers

Answer 13

Combustible, low melting point, low solubility in water, high molecular weight, variable molecule size, low compressive strength, low stiffness, high toughness, low density, durable, low thermal conductivity, electrical insulators, low permeability, flexible

Question 14

How much plastic by percentage is used for building and construction

Answer 14

23%, second largest sector behind packaging

Question 15

give examples of additives

Answer 15

plasticisers (adds flexibility), antioxidants, pigments, fillers

Question 16

How does extrusion form plastic into certain shapes

Answer 16

Plastic granules are fed into a hopper which leads to a screw. The screw heats and squeezes the plastic, melting it. The melt is then passed into a die to form the desired shape

Question 17

How does injection form plastic into certain shapes

Answer 17

Plastic granules are fed into a hopper which leads to a screw. The screw heats and squeezes the plastic, melting it, which is then injected into a mould

Question 18

How does compression moulding form plastic into certain shapes

Answer 18

The plastic sheet or block is squished by compression into the desired shape

Question 19

What is the main plastic in construction

Answer 19

PVC

Question 20

How is HDPE used in landfills

Answer 20

It is used as a flexible, protective liner from leachate

Question 21

What type of plastic is polyethylene and what is it made from

Answer 21

thermoplastic, contains hydrogen and carbon and no oxygen because it is formed from ethene monomers

Question 22

What is the main use of bitumen is civil engineering

Answer 22

The binder of asphalt

Question 23

Properties of bitumen

Answer 23

softens when heated, is a viscous liquid , formed from the heaviest oil fraction in crude oil, black, excellent waterproofing and adhesive properties

Question 24

what happens to the viscosity of bitumen with temperature

Answer 24

Increases when cooled down

Question 25

What happens when the bitumen content in asphalt filling is too high or too low

Answer 25

Too high and the properties of bitumen dominate over the aggregate, too little and the aggregates dont bind (this can be used to make porous asphalt, for drainage)