Step 1: Understanding the Question:
Polyesters are polymers containing the ester functional group in their main chain.
Step 2: Detailed Explanation:
- PHBV (Poly-hydroxybutyrate-co-hydroxyvalerate): It is a copolymer of 3-hydroxybutanoic acid and 3-hydroxypentanoic acid. These monomers are joined by ester linkages, making it a biodegradable polyester.
- Urea formaldehyde: This is a thermosetting resin, not a polyester.
- Thermocol: This is expanded polystyrene, an addition polymer.
- Polyacrylonitrile (PAN): Also known as Orlon or Acrilan, it is an addition polymer of acrylonitrile.
Step 3: Final Answer:
PHBV is a polyester fibre.