---
title: "Biodegradable polymers; Nylon and Teflon"
subject: "Engineering Chemistry"
chapter: 4
key: "semester_2/engineering_chemistry:biodeg-nylon-teflon"
source: https://www.bctengineer.com/q/semester_2/engineering_chemistry/biodeg-nylon-teflon
site: BCT Engineering
---

# Biodegradable polymers; Nylon and Teflon

Engineering Chemistry · Chapter 4: Engineering Polymers

- Asked in: 2073 Magh, 1+4 marks
- Video: [L 10 Elementary idea of Biodegradable polymers, prep, properties & uses - PVC, PMMA, Teflon, Nylon 6](https://www.youtube.com/watch?v=Gr96uA6LbVs) — My show tv
- Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_2/engineering_chemistry/biodeg-nylon-teflon
- Whole chapter: https://www.bctengineer.com/md/semester_2/engineering_chemistry/chapter-4

## Question

What are biodegradable polymers? Write down the preparation and uses of Nylon and Teflon.

## Short answer

Biodegradable polymers are decomposed by microorganisms; e.g., PHBV. Nylon 6,6 is made by condensation of hexamethylenediamine and adipic acid; used for fibres, ropes. Teflon (PTFE) is an addition polymer of tetrafluoroethylene, chemically inert, low friction, heat-resistant; used for non-stick coatings, seals.

## Answer

#### Biodegradable polymers
**Biodegradable polymers** are polymers that can be broken down by the action of microorganisms (bacteria, fungi) and enzymes in the environment into CO₂, water and biomass. They contain links such as ester or amide groups that enzymes can attack.

Examples: **PHBV** (poly-β-hydroxybutyrate-co-β-hydroxyvalerate; from 3-hydroxybutanoic and 3-hydroxypentanoic acids), polylactic acid (PLA), polycaprolactone, starch- and cellulose-based plastics, and nylon-2-nylon-6 (glycine + aminocaproic acid). Uses: packaging, carry bags, disposable cutlery, surgical sutures, implants, and controlled drug delivery capsules.

#### Nylon 6,6
**Nylon 6,6** is a polyamide made by condensation polymerisation of hexamethylenediamine (6 carbons) and adipic acid (6 carbons) at about 250 °C under pressure:

n H₂N(CH₂)₆NH₂ + n HOOC(CH₂)₄COOH → [–NH(CH₂)₆NH–CO(CH₂)₄CO–]ₙ + 2n H₂O

The repeating unit has the amide (–CONH–) link. (Nylon 6 is made from caprolactam by ring-opening polymerisation.)

**Uses:** Nylon is strong, tough, elastic and abrasion resistant, so it is used for fibres for ropes, fishing nets, socks, stockings and clothes, tyre cord, parachutes, carpets, brush bristles, and moulded gears and bearings.

#### Teflon
**Teflon (PTFE, polytetrafluoroethylene)** is made by free-radical **addition polymerisation** of tetrafluoroethylene (TFE) using a persulphate initiator under pressure:

n CF₂=CF₂ → [–CF₂–CF₂–]ₙ

TFE itself is obtained by heating chlorodifluoromethane (CHClF₂) at 600–800 °C.

**Uses:** PTFE is chemically inert, heat resistant (up to 260 °C, m.p. 327 °C), has a very low coefficient of friction and is an excellent electrical insulator. It is used for non-stick coating on cookware, gaskets and seals, insulation of wires and cables, lining of chemical equipment, bearings, valves and surgical implants.

## Check yourself

The answer's key points as multiple-choice questions, with the correct option and why.

1. What defines a biodegradable polymer?
   A. Broken down by microorganisms and enzymes into CO2, water and biomass
   B. Never decomposes
   C. Dissolves only in acids
   D. Melts at low temperature
   Answer: A. Biodegradable polymers are decomposed by microbes into simple harmless products. (Key point: Biodegradable definition)

2. What is released when nylon 6,6 forms?
   A. HCl
   B. CO2
   C. Water (2n H2O)
   D. Nothing
   Answer: C. Condensation of diamine and adipic acid releases water. (Key point: Nylon 6,6 preparation)

3. How is nylon 6 made?
   A. From hexamethylenediamine and adipic acid
   B. From caprolactam by ring-opening polymerisation
   C. From TFE
   D. From phenol
   Answer: B. Nylon 6 comes from caprolactam by ring-opening. (Key point: Nylon 6)

4. What initiator is used for PTFE?
   A. Benzoyl peroxide at 80 C only
   B. A persulphate under pressure
   C. NaOH
   D. AlCl3
   Answer: B. Free-radical addition of TFE with a persulphate initiator under pressure. (Key point: Teflon preparation)

## Related in Engineering Chemistry

- [Nylon, Teflon and epoxy resin](https://www.bctengineer.com/question.md?key=semester_2%2Fengineering_chemistry%3Anylon-teflon-epoxy) — Engineering Chemistry, chapter 4
- [Biodegradable polymers; epoxy resin and polystyrene](https://www.bctengineer.com/question.md?key=semester_2%2Fengineering_chemistry%3Abiodeg-epoxy-polystyrene) — Engineering Chemistry, chapter 4
- [Biodegradable vs non-biodegradable polymers](https://www.bctengineer.com/question.md?key=semester_2%2Fengineering_chemistry%3Abiodeg-nonbiodeg-examples) — Engineering Chemistry, chapter 4, asked 2×
- [Biodegradable polymer; carbon reinforced polymers, chalcogenide glasses](https://www.bctengineer.com/question.md?key=semester_2%2Fengineering_chemistry%3Abiodegradable-carbon-chalcogenide) — Engineering Chemistry, chapter 4
- [Non-biodegradable polymers and demerits](https://www.bctengineer.com/question.md?key=semester_2%2Fengineering_chemistry%3Anon-biodegradable) — Engineering Chemistry, chapter 4
- [Conducting and biodegradable polymers; applications](https://www.bctengineer.com/question.md?key=semester_2%2Fengineering_chemistry%3Aconducting-biodegradable) — Engineering Chemistry, chapter 4