---
title: "Biodegradable vs non-biodegradable polymers"
subject: "Engineering Chemistry"
chapter: 4
key: "semester_2/engineering_chemistry:biodeg-nonbiodeg-examples"
source: https://www.bctengineer.com/q/semester_2/engineering_chemistry/biodeg-nonbiodeg-examples
site: BCT Engineering
---

# Biodegradable vs non-biodegradable polymers

Engineering Chemistry · Chapter 4: Engineering Polymers

- Asked in: 2072 Magh, 2.5 marks; 2069 Poush, 2.5 marks (asked 2 times)
- Video: [Biodegradable Polymers | Engineering Chemistry | Semester exams](https://www.youtube.com/watch?v=i1gfldG6WGo) — Last Moment Engineers
- Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_2/engineering_chemistry/biodeg-nonbiodeg-examples
- Whole chapter: https://www.bctengineer.com/md/semester_2/engineering_chemistry/chapter-4

## Question

Give an account for the biodegradable and non-biodegradable polymers with suitable examples.

## Short answer

Biodegradable polymers, such as PHBV, PLA, and nylon-2-nylon-6, are decomposed by microorganisms into CO2 and water. Non-biodegradable polymers, like polyethylene, PVC, and polystyrene, persist for centuries, causing pollution. The former contain ester or amide links susceptible to enzyme attack.

## 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.

#### Non-biodegradable polymers
**Non-biodegradable polymers** are polymers that cannot be decomposed by microorganisms and stay in the environment for hundreds of years. Most have stable C–C backbones. Examples: polyethylene, polypropylene, PVC, polystyrene, PTFE, nylon 6,6, Bakelite.

**Demerits**
- Accumulate as solid waste in land, rivers and oceans, causing plastic pollution, choking drains (which leads to urban flooding) and harming animals that swallow them.
- Reduce soil fertility and block water seeping into the ground.
- Burning releases toxic gases (CO, dioxins, HCl from PVC, HCN) and CO₂.
- Break into microplastics that enter the food chain.
- Recycling is difficult and costly, especially for thermosetting plastics.

| Point | Biodegradable | Non-biodegradable |
|---|---|---|
| Decomposition | By microorganisms in months to years | Not decomposed; persist for centuries |
| Examples | PHBV, PLA, nylon-2-nylon-6 | PE, PVC, polystyrene, Teflon |
| Environment | Eco-friendly | Cause plastic pollution |

## Check yourself

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

1. Why can microorganisms degrade biodegradable polymers?
   A. They have only C-C backbones
   B. They contain groups such as ester or amide that enzymes can attack
   C. They are metals
   D. They are thermosetting
   Answer: B. Ester and amide groups are attacked by enzymes, breaking the polymer to CO2, water and biomass. (Key point: Why biodegradable)

2. Which set contains only biodegradable polymers?
   A. PE, PVC, PTFE
   B. Bakelite, polystyrene, nylon 6,6
   C. PHBV, PLA, nylon-2-nylon-6
   D. PP, PHBV, Teflon
   Answer: C. PHBV, PLA and nylon-2-nylon-6 are biodegradable; the others are not. (Key point: Examples)

3. What feature of non-biodegradable polymers explains their persistence?
   A. Hydrolysable ester links
   B. Stable C-C backbones that microorganisms cannot decompose
   C. Presence of enzymes
   D. Low molecular mass
   Answer: B. Stable C-C backbones resist microbial attack so they persist for centuries. (Key point: Non-biodegradable backbone)

4. What is a hazard of burning non-biodegradable plastics?
   A. Only water vapour is released
   B. Release of toxic gases such as dioxins and HCl (from PVC)
   C. Fertile soil is produced
   D. Oxygen is released
   Answer: B. Burning gives CO, dioxins, HCl from PVC, HCN and CO2. (Key point: Demerit of burning)

## Related in Engineering Chemistry

- [Non-biodegradable polymers and demerits](https://www.bctengineer.com/question.md?key=semester_2%2Fengineering_chemistry%3Anon-biodegradable) — Engineering Chemistry, chapter 4
- [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
- [Biodegradable polymers; Nylon and Teflon](https://www.bctengineer.com/question.md?key=semester_2%2Fengineering_chemistry%3Abiodeg-nylon-teflon) — 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
- [Conducting and biodegradable polymers; applications](https://www.bctengineer.com/question.md?key=semester_2%2Fengineering_chemistry%3Aconducting-biodegradable) — Engineering Chemistry, chapter 4
- [Thermosetting vs thermoplastics; polymers for ropes, utensils](https://www.bctengineer.com/question.md?key=semester_2%2Fengineering_chemistry%3Athermo-nylon-teflon) — Engineering Chemistry, chapter 4

## Related in other subjects

- [Unique vs non-unique address decoding](https://www.bctengineer.com/question.md?key=semester_5%2Finstrumentation_ii%3Aunique-vs-nonunique-decoding) — Instrumentation II, chapter 2