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Epoxy resin preparation and uses

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.

Mention preparation and uses of epoxy resin.

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):

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.

✓ Answer checked by Claude Opus 5.5 (high effort)

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