Exam Style Questions: Performance Characteristics of Polymers, Biodegradable Polymers, Polymer-Based Sheet And Film Flashcards
Explain the difference between the terms, transparency and translucency (2 marks)
- Transparent material allows light to pass through a material and enables a clear view through the material
- Translucent material only allows a little bit of light to travel through it, often with a degree of fuzziness and obscuring the view through to some extent
Many polymers are flexible and can be used to form hinges.
Explain one disadvantage of using polymers to make hinges. (2 marks)
Polymers have a tendency to work harden as they are folded backward and forwards (1) which means the material can become brittle/stiff/hard and may break (1).
Additives are blended into polymers for many reasons.
Name four different additives in the grid below and state one benefit for its inclusion. (8 marks)
Additive:
Benefits:
Additive: Fire Retardant
Benefits: To reduce the risk of fire / reduce flammability / reduce toxic fumes released when burnt
Additive: Plasticisers
Benefits: To enhance flow characteristics and enable polymers to be moulded at
higher temperatures
Additive: Thermal antioxidants
Benefits: To help to prevent oxidation due to heat exposure during the manufacturing process
Additive: Lubricants
Benefits: To improve polymer flow during moulding by decreasing viscosity
Additive: Antioxidants
Benefits: To reduce the degradation and deterioration from exposure to air and water and help prevent cracking and discoloration
Additive: UV light stabilisers
Benefits: To improve the material’s resistance to degradation by UV light
Additive: Plasticisers
Benefits: To make materials stretch/flow
Additive: Antistatic additives
Benefits: To reduce the build-up of static charge
Additive: Fillers
Benefits: To add bulk and improve the properties of polymers, reducing the amount of polymer used and thus weight and costs
Additive: Bio-batch materials
Benefits: To encourage biodegradability at end of use
Give one source of natural polymers. (1 mark)
- Trees
- Animals
- Humans
This question is about thermoplastics.
(a) What is polymerisation? (3 marks)
(b) Explain using notes and sketches how the polymer chains in thermoplastics are connected and how this affects the way they behave. (3 marks)
a) It is the chemical process of joining monomers together (1) end to end (1) to create long-chain polymers (1).
b) In thermoplastics, polymer chains are loosely entangled with allowing chains to slide over each other when heated (1). This means thermoplastics can be formed
using heat and reshaped many times without changing their properties (1). [For the last mark, google a diagram of polymer chains in thermoplastics to check if you have got it correct]
Name one polymer that is commonly used in the manufacture of ropes for use in the marine industry and explain what properties make them suitable for this application. (2 marks)
Award 1 mark for naming the polymer and a further 1 mark for a relevant explanation.
Nylon – Nylon has a low coefficient of friction, it is durable and resistant to abrasion,
lightweight and it floats on water.
PP Polypropylene – flexible polymer with excellent fatigue resistance, is resistant to
chemicals and solvents, lightweight and floats on water.
This question is about thermosetting plastics.
(a) Name the type of polymerisation used to create thermosets (1 mark)
(b) Explain how cross-linking occurs (1 mark)
(c) What type of reaction is caused? (1 mark)
a) Condensation polymerisation
b) A chemical catalyst is used to cure the polymer causing cross-linking to occur
c) An exothermic reaction
With reference to both the physical and mechanical properties, evaluate the use of urea formaldehyde (UF) is used for plug sockets (2 marks)
Award 1 mark for each relevant property up to a maximum of 2 marks.
- Urea formaldehyde UF is a hard, opaque resin that can be cast to produce the form of the plug socket
- UF has good resistance to deformation by heat
- UF is an excellent thermal insulator
- UF I an excellent electrical insulator
- UF can be coloured using pigments to increase the visual appeal
Explain one way in which UF is used as an adhesive in the timber industry (2 marks)
Award 1 mark for the usage and a further 1 mark for a relevant explanation
UF is used as an adhesive to bond materials such as:
- MDF where particles of waste material from the timber industry are formed into
a board using heat and pressure
- Plywood where layers of thin timber veneer are laminated to form a board
Suggest and justify an appropriate polymer for use in the manufacture of the contact lens case (3 marks)
Award 1 mark for an appropriate polymer and up to 2 marks for a relevant justification.
Polymer – HDPE has a good strength to weight ratio and so will be light and portable whilst strong enough to protect fragile contents (1).
- It is tough and hard and so can resist impact and will not scratch or dent easily (1).
- It has good chemical resistance and so will not be harmed by contact lens solution (1).
- It is waterproof and impermeable protecting the contents from water, oxygen, and dust (1).
A company designing play areas for primary schools is looking for an alternative surface to the sand currently in place. They have considered tarmac but decided this was too unforgiving a surface when children fall. They have looked at woodchips, however, it was found that this was too messy, and the woodchips could be walked into the school buildings on children’s shoes.
Suggest an alternative surface for the playground, explaining what advantages it has to offer (4 marks)
- Rubber granules or shreds could be used to create a safe playground surface.
- Rubber is more forgiving than tarmac if a child were to fall, it also absorbs impact so is better for running and jumping on.
- The rubber granules come in a variety of colours, so patterns or lettering can be created to make the playground more appealing.
- Granules are mixed with an adhesive on-site and then poured and left to cure, this is a relatively easy operation.
- It is easy to level uneven ground when pouring and spreading.
- The surface is safe all year round.
- The surface is easy to mend by cutting around the scuffed area and pouring in new granules.
- Recycled rubber can be used for this purpose.
It is a long-lasting surface.
Discuss the advantages and disadvantages of using fluted polypropylene sheet to make wine storage box
Advantages:
- It is lightweight meaning it does not add too much additional weight to the
product
- It is waterproof meaning it will not absorb any split liquids and can be
easily washed or wiped clean
- The fluting adds rigidity to the material without adding weight, so the box
is less likely to buckle
- The material is able to be cut and scored to allow the box to be created
and stored as a flat packed net and then folded constructed as needed
- The material is flexible when folded and can withstand repeated folding
without work hardening to the point of breaking
- The material is impact resistant protecting the glasses if handled
carelessly
Disadvantages:
- Hardwearing, robust plastic creates a sealed crate, if glasses are put away
wet the water won’t evaporate easily
- If folded carelessly new inaccurate folds can be created weakening the
material
- The plastic sheet may become slippery and difficult to hold if wet
- It not folded and interlocked correctly the load may fall out of the bottom
- If too many boxes are stacked one on top of the other, the bottom-most
box may buckle under the strain
Discuss the advantages and disadvantages of using fluted polypropylene sheet to make a wine storage box
Advantages:
- It is lightweight meaning it does not add too much additional weight to the
product
- It is waterproof meaning it will not absorb any split liquids and can be
easily washed or wiped clean
- The fluting adds rigidity to the material without adding weight, so the box
is less likely to buckle
- The material is able to be cut and scored to allow the box to be created
and stored as a flat packed net and then folded constructed as needed
- The material is flexible when folded and can withstand repeated folding
without work hardening to the point of breaking
- The material is impact resistant protecting the glasses if handled
carelessly
Disadvantages:
- Hardwearing, robust plastic creates a sealed crate, if glasses are put away
wet the water won’t evaporate easily
- If folded carelessly new inaccurate folds can be created weakening the
material
- The plastic sheet may become slippery and difficult to hold if wet
- It not folded and interlocked correctly the load may fall out of the bottom
- If too many boxes are stacked one on top of the other, the bottom-most
box may buckle under the strain
Explain two reasons why foam board is an appropriate material to make concept models of some modular storage furniture (4 marks)
Award 1 mark for a reason and 1 mark for an explanation to a maximum of 4 marks.
- It is available in a large flat sheet (1) which means that although the models are likely to be smaller scale, large single pieces can be used to represent the panels rather than having to join sheets, edge on edge (1).
- It is relatively inexpensive (1) and so adaptations and changes can be made where necessary without great cost (1).
- It is easy to cut using a scalpel, straight edge, and cutting mat (1) It has a good uniform thickness which means you can get a consistent, clean-cut (1).
- It is easy to join using adhesive, tape, or by creating slots (1) enabling the model maker to create 3D forms (1).
- It has an excellent flat surface finish (1) which could be laminated, painted, or printed to represent different materials (1).
Explain one reason why solvent-based adhesives are not the best choice for joining foam board. (2 marks
The solvents are likely to dissolve the foam inner (1) which will result in the board collapsing/losing its core strength and rigidity / making parts hard to join (1)