Experiment
Aim: To prepare Phenol formaldehyde (P-F) resin.
Chemicals required: Phenol (2 g), 40% aqueous formaldehyde solution or formalin (2.5
mL), glacial acetic acid (5 mL) and conc. HCl (8 mL).
Theory: Phenol formaldehyde resin or P-F resin or phenolic resins (also called
phenoplasts) are an important class of polymers formed by condensation
polymerization of phenol and formaldehyde in acidic or alkaline medium.
Step 1: Formation of methylol phenol derivative
Initially the monomers combine to form methylol phenol derivatives depending upon
the phenol-to-formaldehyde ratio.
(P/F: 1:1) → 2-Hydroxymethyl phenol / 4-Hydroxymethyl phenol
(P/F: 1:2) → 2,4-Dihydroxymethyl phenol
(P/F: 1:3) → 2,4,6-Dihydroxymethyl phenol
Step 2: The phenol formaldehyde derivatives react among themselves or with phenol to
give a linear polymer or a highly cross-linked polymer.
(a) Linear polymer (Novolac)
Formed by stepwise condensation of methylol phenol units, producing a thermoplastic
polymer.
(b) Cross-linked polymer (Bakelite)
A highly cross-linked thermosetting polymer formed by further condensation of novolac
or methylol derivatives. It was first prepared by Baekeland and can be easily formed if a
curing agent such as hexamethylenetetramine is added during synthesis.
Aim: To prepare Phenol formaldehyde (P-F) resin.
Chemicals required: Phenol (2 g), 40% aqueous formaldehyde solution or formalin (2.5
mL), glacial acetic acid (5 mL) and conc. HCl (8 mL).
Theory: Phenol formaldehyde resin or P-F resin or phenolic resins (also called
phenoplasts) are an important class of polymers formed by condensation
polymerization of phenol and formaldehyde in acidic or alkaline medium.
Step 1: Formation of methylol phenol derivative
Initially the monomers combine to form methylol phenol derivatives depending upon
the phenol-to-formaldehyde ratio.
(P/F: 1:1) → 2-Hydroxymethyl phenol / 4-Hydroxymethyl phenol
(P/F: 1:2) → 2,4-Dihydroxymethyl phenol
(P/F: 1:3) → 2,4,6-Dihydroxymethyl phenol
Step 2: The phenol formaldehyde derivatives react among themselves or with phenol to
give a linear polymer or a highly cross-linked polymer.
(a) Linear polymer (Novolac)
Formed by stepwise condensation of methylol phenol units, producing a thermoplastic
polymer.
(b) Cross-linked polymer (Bakelite)
A highly cross-linked thermosetting polymer formed by further condensation of novolac
or methylol derivatives. It was first prepared by Baekeland and can be easily formed if a
curing agent such as hexamethylenetetramine is added during synthesis.
