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For safety reasons, mouthguards are widely used in sport - Leaving Cert Engineering - Question 6 - 2015
Question 6
For safety reasons, mouthguards are widely used in sport. The mouthguard shown is manufactured from the thermoplastic copolymer, ethylene-vinyl-acetate (EVA). (i) O... show full transcript
Worked Solution & Example Answer:For safety reasons, mouthguards are widely used in sport - Leaving Cert Engineering - Question 6 - 2015
Step 1
Outline any two reasons why EVA is suitable for the manufacture of a mouthguard.
Answer
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Softness and Flexibility: EVA is known for its soft and flexible properties, which provide comfort and protection when worn during sports. Its flexibility allows it to better conform to the shape of the user's teeth and gums, reducing the risk of injury during contact sports.
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Chemical Resistance: EVA exhibits good resistance to chemicals, including saliva and other bodily fluids. This property ensures the durability and hygiene of the mouthguard, as it is less likely to degrade or lose its structural integrity over prolonged use.
Step 2
Describe, with the aid of a diagram, a suitable polymer manufacturing process to mass-produce a thermoplastic mouthguard.
Answer
The Injection Moulding process is suitable for mass production. A diagram can be visualized in the following steps:
- Hopper Feeding: Plastic granules are fed into a hopper.
- Melting: The granules are heated and melted into a molten plastic.
- Injection: The molten plastic is injected into a mould cavity under high pressure.
- Cooling: The material is allowed to cool and solidify in the shaped mould.
- Ejection: The finished mouthguard is ejected from the mould.
This process ensures efficiency and consistency in production, allowing for quick manufacturing of multiple mouthguards.
Step 3
Select any two of the following and distinguish between:
Answer
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Amorphous and crystalline polymer:
- Amorphous Polymers: These do not have a regular pattern in the arrangement of their atoms, leading to a more random structure. They are generally more flexible and transparent.
- Crystalline Polymers: These have a well-defined structure with ordered arrangements of molecules, resulting in higher strength, rigidity, and density.
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Natural and synthetic rubber:
- Natural Rubber: Sourced from the sap of rubber trees, it has a more flexible structure and good tensile strength but can degrade under certain environmental conditions.
- Synthetic Rubber: Manufactured through chemical processes, synthetic rubber can be tailored for specific applications, offering improved durability and resistance to heat and chemicals.
Step 4
Discuss the main properties and the internal structures of each of the following:
Answer
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Thermoplastics:
- Generally have a linear or branched structure, allowing them to melt and re-mold easily.
- Properties: Low melting point, good for easy moulding, low tensile strength, ideal for recycling due to their ability to be re-melted.
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Thermosetting Plastics:
- These have a cross-linked structure that makes them hard and rigid.
- Properties: High melting point, rigidity, excellent thermal insulation, can withstand higher temperatures without softening.
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Elastomers:
- Consist of linear chains that are coiled and subject to minimal cross-linking, giving them their elastic properties.
- Properties: High resilience, soft and deformable, excellent return to shape after deformation, low permeability to gases, suitable for various applications.
Step 5
Describe how the variety of polymers currently available has influenced modern design technology.
Answer
The extensive variety of polymers available today allows for greater flexibility and innovation in design processes. Designers can choose from numerous types of polymers with specific properties to meet the requirements of their projects. For instance, lightweight polymers are prioritized in aerospace and automotive designs for improved fuel efficiency, while high-temperature resistant polymers are favored in electronic applications. Advanced techniques like 3D printing enable the creation of custom shapes and designs directly from digital models, facilitating rapid prototyping and reducing time-to-market. This adaptability not only enhances the functionality of products but also promotes sustainability by allowing for the use of recycled materials and reducing waste.