Plastics; Properties And Shaping Processes
Imagine a plastic water bottle as a polymeric object and complete the below table.
1. What is the name of polymer? Please spell out its full name.
2. What is its abbreviation?
3. What about the crystallinity of this polymer (crystalline, semi-crystalline, amorphous)? Please explain how the crystallinity (%) of this polymer is derived and cite your source here. The answer may depend on how the polymer is synthesized.
4. Is it thermoplastic or thermoset? Please explain the reason why it is thermoplastic or thermoset.
5. What is its melting point ( Tm )? What crystallinity (%) of this polymer is referenced for the melting point measurement here?
6. What is its glass transition temperature ( Tg ) ? How is Tg defined and measured?
7. Is it biodegradable? Why or why not? Cite your source here.
8. What is the name of its shaping process? Please explain the shaping process(es) and list at least 2 products made with the polymer discussed here by this shaping process. Cite your source.
Sample Solution
Polymer Information Table
| Property | Value | Source |
|---|---|---|
| Polymer Name | Polyethylene terephthalate (PET) | Wikipedia: https://en.wikipedia.org/wiki/Polyethylene_terephthalate |
| Abbreviation | PET | |
| Crystallinity | Semi-crystalline | PET is a semi-crystalline polymer, meaning that it has both crystalline and amorphous regions. The crystallinity of PET can vary depending on how it is processed, but it is typically around 30-50%.[1] |
| Type | Thermoplastic | PET is a thermoplastic polymer, meaning that it can be melted and re-shaped multiple times. This is due to the fact that the polymer chains are not cross-linked.[2] |
| Melting Point (Tm) | 257-267°C | Wikipedia: https://en.wikipedia.org/wiki/Polyethylene_terephthalate |
| Glass Transition Temperature (Tg) | 76°C | Wikipedia: https://en.wikipedia.org/wiki/Polyethylene_terephthalate |
| Biodegradable | No | PET is not biodegradable, meaning that it does not break down naturally in the environment. This is due to the fact that the polymer chains are very strong and resistant to degradation.[3] |
Shaping Processes
PET can be shaped into various products using a variety of processes, including:
- Injection molding: This process is used to make a wide variety of products, including plastic water bottles, food containers, and toys.
Full Answer Section
- Blow molding: This process is used to make hollow plastic products, such as bottles and jars.
- Extrusion: This process is used to make continuous plastic products, such as films and sheets.
Examples of Products Made with PET
- Plastic water bottles
- Food containers
- Toys
- Medical devices
- Clothing fibers
- Industrial packaging
Conclusion
PET is a versatile and widely used polymer with a variety of properties that make it suitable for a wide range of applications. It is important to note that PET is not biodegradable, so it is important to recycle PET products whenever possible.