---
title: "Biodegradable polymer; carbon reinforced polymers, chalcogenide glasses"
subject: "Engineering Chemistry"
chapter: 4
key: "semester_2/engineering_chemistry:biodegradable-carbon-chalcogenide"
source: https://www.bctengineer.com/q/semester_2/engineering_chemistry/biodegradable-carbon-chalcogenide
site: BCT Engineering
---

# Biodegradable polymer; carbon reinforced polymers, chalcogenide glasses

Engineering Chemistry · Chapter 4: Engineering Polymers

- Asked in: 2074 Bhadra, 5 marks
- 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/biodegradable-carbon-chalcogenide
- Whole chapter: https://www.bctengineer.com/md/semester_2/engineering_chemistry/chapter-4

## Question

What is biodegradable polymer? Write applications of carbon reinforced polymers and chalcogenide glasses in engineering.

## Short answer

Biodegradable polymers like PHBV and PLA are decomposed by microorganisms. Carbon-fiber reinforced polymers are used in aircraft, racing cars, and wind turbines due to high strength-to-weight. Chalcogenide glasses find applications in infrared optics, thermal imaging, and phase-change memory.

## Answer

#### Biodegradable polymer
**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.

#### Applications of carbon-reinforced polymers
Carbon-fibre reinforced polymers (CFRP, carbon fibres in epoxy) are extremely strong and light, stiff, fatigue and corrosion resistant:
- Aircraft and spacecraft parts, helicopter blades, rocket motor casings.
- Racing cars, bicycles, tennis rackets and golf shafts.
- Strengthening of bridges and buildings, wind turbine blades.
- Artificial limbs, and X-ray-transparent medical tables.

#### Applications of chalcogenide glasses
- Infrared lenses and windows for thermal imaging and night vision.
- IR optical fibres.
- Phase-change memory and rewritable optical discs.
- Photoreceptors of photocopiers; switching devices and sensors.

## Check yourself

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

1. What does a biodegradable polymer break down into?
   A. Toxic metals
   B. CO2, water and biomass by microorganisms and enzymes
   C. Only carbon black
   D. Microplastics
   Answer: B. Microbes and enzymes degrade them into CO2, water and biomass. (Key point: Biodegradable polymer)

2. Which describes CFRP?
   A. Carbon fibres in an epoxy matrix; strong, light, stiff and corrosion resistant
   B. Glass fibres in rubber
   C. Carbon blocks in metal
   D. Silicon fibres in PVC
   Answer: A. CFRP is carbon fibre in epoxy, extremely strong and light. (Key point: CFRP)

3. Which is an application of CFRP?
   A. Non-stick coating
   B. Rocket motor casings and wind turbine blades
   C. Disposable cutlery
   D. Mattress foam
   Answer: B. CFRP is used in aerospace parts, rocket casings, and wind turbine blades. (Key point: CFRP use)

4. Which application suits chalcogenide glasses?
   A. Window glass for houses
   B. Visible-light lenses only
   C. Infrared lenses for thermal imaging and night vision
   D. Rubber seals
   Answer: C. They transmit infrared, used in IR lenses, fibres and phase-change memory. (Key point: Chalcogenide use)

## Related in Engineering Chemistry

- [Chalcogenide glasses and network polymers of sulphur](https://www.bctengineer.com/question.md?key=semester_2%2Fengineering_chemistry%3Achalcogenide-glass-polymers) — 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
- [Fiber reinforced polymers and applications](https://www.bctengineer.com/question.md?key=semester_2%2Fengineering_chemistry%3Afiber-reinforced) — Engineering Chemistry, chapter 4, asked 2×
- [Short note: Chalcogenide glasses](https://www.bctengineer.com/question.md?key=semester_2%2Fengineering_chemistry%3Achalcogenide-glasses) — Engineering Chemistry, chapter 4, asked 3×
- [Cross linked polymer; inorganic polymer; chalcogenide](https://www.bctengineer.com/question.md?key=semester_2%2Fengineering_chemistry%3Acrosslinked-inorganic-chalcogenide) — Engineering Chemistry, chapter 4
- [Engineering applications of PVC and conducting polymer](https://www.bctengineer.com/question.md?key=semester_2%2Fengineering_chemistry%3Apvc-conducting-polymer) — Engineering Chemistry, chapter 4