---
title: "Short notes: Bakelite and Teflon"
subject: "Engineering Chemistry"
chapter: 4
key: "semester_2/engineering_chemistry:bakelite-teflon"
source: https://www.bctengineer.com/q/semester_2/engineering_chemistry/bakelite-teflon
site: BCT Engineering
---

# Short notes: Bakelite and Teflon

Engineering Chemistry · Chapter 4: Engineering Polymers

- Asked in: 2073 Bhadra, 2.5+2.5 marks
- Video: [PVC, Teflon, Nylon 6, Nylon 6,6 , Polyester, PMMA &  bakelite Preparation and uses | Chemistry RGPV](https://www.youtube.com/watch?v=c5IpEIjUaDA) — Jishan Ahmad Education
- Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_2/engineering_chemistry/bakelite-teflon
- Whole chapter: https://www.bctengineer.com/md/semester_2/engineering_chemistry/chapter-4

## Question

Write short notes on Bakelite and Teflon.

## Short answer

Bakelite: thermosetting phenol–formaldehyde resin made by condensation polymerisation, cross-linked 3D network, hard, heat-resistant, used for electrical switches and handles. Teflon (PTFE): addition polymer of tetrafluoroethylene, chemically inert, very low friction, heat-resistant to 260 °C, used for non-stick coatings, insulation, and seals.

## Answer

#### Bakelite
Bakelite is a phenol–formaldehyde resin, the first fully synthetic thermosetting plastic. It is made by **condensation polymerisation** of phenol and formaldehyde (methanal).

1. Phenol reacts with formaldehyde (acid or base catalyst) to give o- and p-hydroxymethyl phenols:
   C₆H₅OH + HCHO → HOCH₂–C₆H₄–OH
2. These condense with more phenol with loss of water, forming a linear, low molecular mass prepolymer (novolac with an acid catalyst and excess phenol; resole with a base catalyst and excess formaldehyde).
3. On heating with a hardener (hexamethylenetetramine for novolac) or just heat for resole, –CH₂– bridges form between the rings at the o- and p-positions, giving a hard, **cross-linked three-dimensional network**.

```text
   OH         OH         OH
   |          |          |
  (C₆H₃)–CH₂–(C₆H₃)–CH₂–(C₆H₃)–   (rings joined by –CH₂–;
         |            |            more CH₂ bridges cross-link
        CH₂          CH₂           the chains in 3-D)
```
n C₆H₅OH + n HCHO → [C₆H₃(OH)–CH₂]ₙ + n H₂O (simplified)

Bakelite is hard, rigid, heat resistant, a good electrical insulator, and does not soften on reheating. Uses:
- Electrical switches, plugs, sockets, switch-boards and insulating parts of computers and appliances.
- Handles of cookers, pans and irons.
- Laminates (e.g. phenolic printed circuit boards), brake linings, and adhesive for plywood.
- Telephone cases, radio cabinets, billiard balls, 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.

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. Uses: 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. Bakelite is which kind of plastic?
   A. Thermoplastic addition polymer
   B. Thermosetting phenol-formaldehyde condensation resin
   C. Biodegradable polyester
   D. Elastomer
   Answer: B. Bakelite is the first fully synthetic thermosetting phenol-formaldehyde resin. (Key point: Bakelite classification)

2. Which catalyst and ratio gives the novolac prepolymer?
   A. Base catalyst and excess formaldehyde
   B. Acid catalyst and excess phenol
   C. No catalyst
   D. Acid catalyst and excess formaldehyde
   Answer: B. Novolac uses acid and excess phenol; resole uses base and excess formaldehyde. (Key point: Novolac vs resole)

3. What is the monomer of Teflon?
   A. Styrene
   B. Ethylene
   C. Tetrafluoroethylene CF2=CF2
   D. Vinyl chloride
   Answer: C. PTFE is the addition polymer of CF2=CF2. (Key point: Teflon monomer)

4. Which property explains non-stick use of PTFE?
   A. High friction
   B. Very low coefficient of friction and chemical inertness
   C. Solubility in water
   D. Low melting point
   Answer: B. PTFE is inert, heat resistant and has a very low coefficient of friction. (Key point: Teflon properties)