---
title: "Classification of plastics with examples"
subject: "Civil Engineering Materials"
chapter: 10
key: "semester_3/civil_engineering_materials:plastics-classification-examples"
source: https://www.bctengineer.com/q/semester_3/civil_engineering_materials/plastics-classification-examples
site: BCT Engineering
---

# Classification of plastics with examples

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

- Asked in: 2068 Baisakh, 3+1+1 marks
- 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/plastics-classification-examples
- Whole chapter: https://www.bctengineer.com/md/semester_3/civil_engineering_materials/chapter-10

## Question

Distinguish between two major classifications of plastics. Name two popular plastics of each type and indicate their uses.

## Short answer

Thermoplastics soften when heated and harden on cooling, e.g., PVC (pipes) and polyethylene (tanks). Thermosetting plastics set permanently on heating and cannot be remolded, e.g., bakelite (electrical switches) and epoxy resin (adhesives, concrete repair).

## Answer

Plastics are classified into two major groups based on how they behave on heating: thermoplastics and thermosetting plastics.

| Point | Thermoplastics | Thermosetting plastics |
|---|---|---|
| Behaviour | Soften on heating, harden on cooling, repeatable | Set permanently on heating; cannot be softened again |
| Structure | Linear chains | Cross-linked network |
| Properties | Soft, flexible, recyclable | Hard, rigid, heat resistant |

#### Popular plastics and uses

**Thermoplastics**

- **PVC:** pipes, conduits, flooring, window frames.
- **Polyethylene:** water tanks, DPC sheets, geomembranes.

**Thermosetting plastics**

- **Bakelite (phenol formaldehyde):** electrical switches, sockets, handles, laminates.
- **Epoxy resin:** adhesives, floor coatings, concrete repair, FRP.

## Check yourself

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

1. On what basis are plastics classified into the two major groups?
   A. Their colour
   B. Their behaviour on heating
   C. Their cost
   D. Their source of petroleum
   Answer: B. Plastics are grouped as thermoplastics or thermosetting plastics according to how they behave on heating. (Key point: Basis of classification)

2. Which pair is a correct thermoplastic with a use?
   A. Bakelite: electrical switches
   B. Epoxy resin: adhesives
   C. PVC: pipes, conduits, flooring, window frames
   D. Epoxy resin: water tanks
   Answer: C. PVC and polyethylene are thermoplastics; Bakelite and epoxy are thermosets. (Key point: Thermoplastic examples and uses)

3. Which is a thermosetting plastic with a correct use?
   A. Epoxy resin: adhesives, floor coatings, concrete repair
   B. Polyethylene: geomembranes
   C. PVC: conduits
   D. Polyethylene: DPC sheets
   Answer: A. Epoxy resin and Bakelite (phenol formaldehyde) are thermosets, used for adhesives, coatings and switches. (Key point: Thermosetting examples and uses)

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