This question is about polymers.
Polyesters are condensation polymers. When the monomers react together, a small molecule is lost.
Name a small molecule that can be lost during the formation of a polyester.
Poly(tetrafluoroethene) (PTFE) is an addition polymer produced from tetrafluoroethene.
Complete the structure of poly(tetrafluoroethene) in the polymerisation equation below:
Disposable take-away food containers can be made from:
- expanded polystyrene
- sugarcane bagasse (a natural plant fibre)
- a mixture of recycled polystyrene and sugarcane bagasse
Recycled polystyrene is more durable and water-resistant than sugarcane bagasse.
A container made from a mixture of recycled polystyrene and sugarcane bagasse is more sustainable than using 100% brand new polystyrene or 100% sugarcane bagasse.
Suggest why.
Surgical sutures (stitches) are used to hold body tissues together after surgery or injury. Some sutures are designed to dissolve inside the body, while others must be removed later.
The table below shows some properties of two polymer fibres used for surgical sutures.
| Property | Polyglycolic acid (PGA) (a polyester) | Nylon (a polyamide) |
|---|---|---|
| Tensile strength in MPa\text{MPa}MPa | 800800800 | 400400400 |
| Biodegradability (in contact with body fluids) | Hydrolysed and absorbed by body tissues within 60 to 90 days | Highly stable, does not break down over time |
| Flexibility and knot security | Excellent (knots stay tight and secure) | Moderate (stiffer, knots can tend to slip open) |
| Tissue reaction / inflammation | Extremely low | Low |
Evaluate the suitability of polyglycolic acid (PGA) and nylon for use as surgical sutures.