---
title: "Short note: types of plastic materials"
subject: "Civil Engineering Materials"
chapter: 10
key: "semester_3/civil_engineering_materials:types-of-plastic"
source: https://www.bctengineer.com/q/semester_3/civil_engineering_materials/types-of-plastic
site: BCT Engineering
---

# Short note: types of plastic materials

Civil Engineering Materials · Chapter 10: Asphalt, Bitumen, Tar and Miscellaneous Materials

- Asked in: 2081 Chaitra (new course), 2 marks; 2081 Bhadra, 2 marks (asked 2 times)
- Video: [What are the Different Types of Plastics | 7 Types of Plastic and Categories](https://www.youtube.com/watch?v=LPThrGVMARA) — Plascon Plastics
- Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_3/civil_engineering_materials/types-of-plastic
- Whole chapter: https://www.bctengineer.com/md/semester_3/civil_engineering_materials/chapter-10

## Question

Write a short note on types of plastic materials.

## Short answer

Plastics are classed as thermoplastics (soften on heating, remouldable; e.g., PVC, polyethylene, polystyrene) and thermosetting plastics (set permanently on first heating; e.g., bakelite, melamine, epoxy).

## Answer

Plastics are polymers that can be moulded under heat and pressure. They are of two main types:

#### Thermoplastics

Soften on heating and harden on cooling, and the process is repeatable. They can be remoulded and recycled. Examples:

- Polyvinyl chloride (PVC): pipes, conduits, floor tiles
- Polyethylene (PE/HDPE): water tanks, DPC sheet, pipes
- Polystyrene: insulation boards (thermocol)
- Acrylic (PMMA): sheets, skylights, glazing
- Polypropylene, nylon

#### Thermosetting plastics

Set permanently on first heating and cannot be softened again; they have cross-linked molecules, are harder and heat-resistant. Examples:

- Bakelite (phenol formaldehyde): switches, handles
- Urea formaldehyde: adhesives, laminates
- Melamine formaldehyde: laminates (Formica), tableware
- Epoxy resin: adhesives, floor coatings
- Polyester resin: fibre-glass reinforced plastics (GRP)

## Check yourself

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

1. Thermoplastics do what on heating?
   A. Set permanently
   B. Soften and can be remoulded repeatedly
   C. Burn
   D. Harden
   Answer: B. They soften on heating and harden on cooling, repeatably. (Key point: Thermoplastics)

2. Why can thermosetting plastics not be resoftened?
   A. Linear molecules
   B. Cross-linked molecules set permanently
   C. They are liquids
   D. They contain water
   Answer: B. Cross-linked molecules set permanently on first heating. (Key point: Thermosetting)

3. Which is thermosetting?
   A. PVC
   B. Polyethylene
   C. Bakelite
   D. Acrylic
   Answer: C. Bakelite, urea and melamine formaldehyde, epoxy and polyester are thermosetting. (Key point: Examples)

## Related in Civil Engineering Materials

- [Short note: elastic and plastic behaviour](https://www.bctengineer.com/question.md?key=semester_3%2Fcivil_engineering_materials%3Aelastic-plastic-behaviour) — Civil Engineering Materials, chapter 1
- [Define thermosetting plastic](https://www.bctengineer.com/question.md?key=semester_3%2Fcivil_engineering_materials%3Athermosetting-plastic-define) — Civil Engineering Materials, chapter 10
- [Define plastic material](https://www.bctengineer.com/question.md?key=semester_3%2Fcivil_engineering_materials%3Adefine-plastic-material) — Civil Engineering Materials, chapter 10

## Related in other subjects

- [Plastic torque of solid shaft is 4/3](https://www.bctengineer.com/question.md?key=semester_3%2Fstrength_of_materials%3Aplastic-torque-solid-shaft-4-3) — Strength of Materials, chapter 6
- [Limiting plastic moment is 1.5 times elastic moment](https://www.bctengineer.com/question.md?key=semester_3%2Fstrength_of_materials%3Aplastic-moment-rectangular-1-5) — Strength of Materials, chapter 7
- [Define plastic moment capacity of beam](https://www.bctengineer.com/question.md?key=semester_3%2Fstrength_of_materials%3Aplastic-moment-capacity-definition) — Strength of Materials, chapter 7