---
title: "Epoxy resin preparation and uses"
subject: "Engineering Chemistry"
chapter: 4
key: "semester_2/engineering_chemistry:epoxy-resin"
source: https://www.bctengineer.com/q/semester_2/engineering_chemistry/epoxy-resin
site: BCT Engineering
---

# Epoxy resin preparation and uses

Engineering Chemistry · Chapter 4: Engineering Polymers

- Asked in: 2071 Bhadra, 2 marks; 2069 Poush, 2.5 marks (asked 2 times)
- Video: [Trick to learn, Epoxy Resin | Preparation , Application , Property | Easy Concept.](https://www.youtube.com/watch?v=dm3LHUdEdq0) — Mr. Astrophile
- Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_2/engineering_chemistry/epoxy-resin
- Whole chapter: https://www.bctengineer.com/md/semester_2/engineering_chemistry/chapter-4

## Question

Mention preparation and uses of epoxy resin.

## Short answer

Epoxy resin is prepared by condensing bisphenol-A and epichlorohydrin in NaOH, yielding a prepolymer with epoxide end groups; curing with polyamine hardeners forms a crosslinked network. Uses include strong adhesives (Araldite), surface coatings, electrical insulation, and matrix for fiber-reinforced composites.

## Answer

#### Preparation
Epoxy resins are thermosetting polymers containing epoxide (oxirane) groups. They are made by condensing **bisphenol-A** with **epichlorohydrin** in presence of NaOH (about 50–60 °C):

```text
HO–R–OH + 2 ClCH₂–CH–CH₂   --NaOH, –2HCl-->
(bisphenol-A)      \ /
                    O  (epichlorohydrin)

CH₂–CH–CH₂–O–R–O–CH₂–CH–CH₂    (n = 0)
  \ /                 \ /
   O                   O
where R = C₆H₄–C(CH₃)₂–C₆H₄
Higher polymers: more –CH₂–CH(OH)–CH₂–O–R–O– units inside.
```
The product is a liquid or low-melting prepolymer with epoxide end groups. It is **cured** (hardened) by adding a hardener such as a polyamine (ethylenediamine, triethylenetetramine) or an acid anhydride, which opens the epoxide rings and forms a cross-linked network.

#### Uses
- Strong adhesives (Araldite) for metal, glass and ceramics.
- Surface coatings, paints and protective linings for tanks and pipes.
- Electrical insulation and potting of electronic components; glass-epoxy laminates for printed circuit boards.
- Matrix of fibre-reinforced composites (aircraft, boats, sports goods).
- Flooring, castings, moulds and tools.

## Check yourself

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

1. Which pair of reactants forms the epoxy prepolymer?
   A. Phenol and formaldehyde
   B. Bisphenol-A and epichlorohydrin with NaOH
   C. Adipic acid and hexamethylenediamine
   D. Styrene and benzoyl peroxide
   Answer: B. Epoxy resin is made by condensing bisphenol-A with epichlorohydrin in presence of NaOH, losing HCl. (Key point: Reactants)

2. What happens during curing of epoxy resin?
   A. A hardener such as a polyamine opens the epoxide rings and forms a cross-linked network
   B. The resin is melted and cooled
   C. Water is removed to give a linear chain
   D. Chlorine is added
   Answer: A. Hardeners like ethylenediamine or anhydrides open epoxide rings to make a cross-linked thermoset. (Key point: Curing)

3. Epoxy resins are classified as which type?
   A. Thermoplastic
   B. Natural rubber
   C. Thermosetting polymer
   D. Biodegradable polymer
   Answer: C. After curing they form a cross-linked network that does not soften on heating. (Key point: Type of polymer)

4. Which is a use of epoxy resin?
   A. Non-stick cookware
   B. Araldite adhesive and glass-epoxy PCB laminates
   C. Rubber tyres
   D. Mattress foam
   Answer: B. Epoxies are strong adhesives (Araldite), coatings and PCB laminates. (Key point: Uses)

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