Preparation of a Phenoplast Resin

Demonstration Experiment on Video

Preparation of a Phenoplast Resin

Objectives: Polycondensation, Thermosetting Plastic

Peter Keusch

German version

Chemicals:
formaldehyde solution 37 %
phenol
ice acetic acid
conc. hydrochloric acid

Glass wares:
2 beakers 50 mL
beaker 100 mL
snap-cap vial 50 mL
glass rod

2 graduated measuring pipets 30 mL
pipet bulb

Hazards and safety precautions:

Formaldehyde solution 37 % is very toxic by inhalation, ingestion and through skin absorption. Readily absorbed through skin. Probable human carcinogen. Mutagen. May cause damage to kidneys, allergic reactions, sensitisation and heritable genetic damage.

Phenol is acute poisoning by ingestion, inhalation or skin contact may lead to death. Phenol is readily absorbed through the skin. Highly toxic by inhalation.

Conc. hydrochloric acid is extremely corrosive. Inhalation of vapour can cause serious injury. Ingestion may be fatal. Liquid can cause severe damage to skin and eyes.

Acetic acid is strongly corrosive and causes serious burns. Lachrymator.

Safety glasses and protective gloves required. The experiment should be performed under a portable fume cupboard giving all-round visibility!

Experimental procedure:

10 g of phenol, 12.5 ml of formaldehyde and 27.5 mL of ice acetic acid are mixed in a beaker. 24 mL of conc. HCl are slowly added to the mixture while stirring.

Result:

After the addition of hydrochloric acid a white substance precipitates. Finaly, a pink colored plastic clump is formed at the bottom of the beaker while stirring. The plastic clump can be fished out wth a glass rod.

Video clip (Download RealPlayer .rm file)

Discussion and background:

The belgian chemist Leo Hendrik Baekeland made experiments with phenol and formaldehyde (1907-1909) and discovered, that the two compounds react with one another under release of heat to form a polymeric plastic.

The structure of a phenoplast resin depends on ortho-para substitution and on the fact that substituting units don't lie in the identical plane as other substituting units. All of this gives the phenoplast 3D structure.

Phenoplast is a heat-resistant, thermosetting, chemically stable resin. It doesn't soften again when heated, rather than a thermo-plastic like styrene.

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