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The vehicle roof box shown is designed to carry luggage and is manufactured from the thermoplastic copolymer, Acrylonitrile Butadiene Styrene (ABS) - Leaving Cert Engineering - Question 6 - 2018
Question 6
The vehicle roof box shown is designed to carry luggage and is manufactured from the thermoplastic copolymer, Acrylonitrile Butadiene Styrene (ABS). (i) Name and de... show full transcript
Worked Solution & Example Answer:The vehicle roof box shown is designed to carry luggage and is manufactured from the thermoplastic copolymer, Acrylonitrile Butadiene Styrene (ABS) - Leaving Cert Engineering - Question 6 - 2018
Step 1
Name and describe, with the aid of a diagram, a polymer manufacturing process suitable for the manufacture of the roof box.
Answer
The suitable polymer manufacturing process for the roof box is Injection Moulding. This method involves the following steps:
- Feeding: Plastic granules are fed into a hopper.
- Melting: Heaters melt the plastic granules into a molten state using heat and friction.
- Injecting: A motor-driven screw injects the molten plastic into a mould cavity designed in the shape of the roof box, ensuring that all spaces are filled.
- Cooling: Once the mould is filled, it is cooled to solidify the plastic.
- Demoulding: The mould opens to eject the finished product.
A diagram illustrating this process would show the hopper, screw, heating elements, and the mould cavity.
Step 2
Step 3
Outline a suitable polymer additive which is used to improve the roof box for each of the following: to provide greater resistance to UV rays.
Answer
To provide greater resistance to UV rays, UV Stabilizers are added. These additives help protect the polymer's properties by absorbing UV radiation, thus reducing degradation.
Step 4
Describe any three of the following: Calendering.
Answer
Calendering is a manufacturing process where thermoplastic sheets are produced by passing the material through a series of heated rollers. This process gradually reduces the thickness of the sheets, allowing for precise control over material specifications and producing uniform thickness.
Step 5
Describe any three of the following: Addition polymerisation.
Answer
Addition polymerisation is a chemical process where small molecules called monomers are joined to form a polymer chain. A common example is the polymerisation of ethylene to produce polyethylene. This reaction involves the breaking of double bonds in monomers, allowing them to connect and form long chains.
Step 6
Describe any three of the following: Glass transition temperature.
Answer
The glass transition temperature (Tg) is the temperature range where a polymer transitions from a hard, glassy state to a soft, rubbery state. Below Tg, the polymer is brittle, and above Tg, it becomes ductile. Understanding Tg helps in determining the thermal properties and applications of different polymers.
Step 7
Describe any three of the following: Van der Waals forces.
Answer
Van der Waals forces are weak intermolecular forces that occur between polymer chains. These forces arise due to temporary dipoles created when electron clouds around atoms fluctuate. While they are weaker than covalent or ionic bonds, they play a crucial role in determining the physical properties of polymers.
Step 8
Explain the term elastomer.
Answer
An elastomer is a type of polymer that exhibits significant elasticity, meaning it can stretch and return to its original shape. Elastomers consist of long, flexible molecular chains that are lightly cross-linked, allowing them to be very elastic at room temperature.
Step 9
Explain the polymer manufacturing process of extrusion and give one reason for using this process to produce elastomer seals.
Answer
In extrusion, thermoplastic polymer is fed into a heated barrel where it is melted and then forced through a die to create continuous shapes, such as pipes or profiles. This process is preferred for elastomer seals as it allows for the production of long, uniform pieces that can be cut to the desired length.
Step 10
Explain two reasons why elastomer seals are used to hold glass panels in frames.
Answer
- Flexibility/Softness: Elastomer seals can accommodate slight movements and vibrations, ensuring a tight fit around glass panels.
- Damping Effect: They help dampen vibrations, protecting the glass from cracking and providing cushioning against hard surfaces.