Lab #9 - Making Glyptal Resin Plastic
Introduction: Phthalic anhydride and Phthalic acid can be used along with glycerol to create a plastic. They are combined and heated in a test tube. A clear plastic that is formed is poured into an aluminum or plastic cap from a plastic soda bottle. A penny is placed in the cap and permanently embedded in the plastic.
Materials: Phthalic acid, glycerol, sodium acetate, old large test tube, plastic bottle cap.
Safety Note: Students should wear goggles and plastic disposable gloves. Avoid breathing the vapours and avoid skin contact with the phthalic acid..
Reaction: this is essentially an
esterification reaction between the glycerol and phthalic anhydride. Water
is produced during esterification and is removed by boiling the mixture.
this plastic, glyptal resin, is a thermosetting plastic formed by phthalic
anhydride acting as a cross-linker to strands of glycerol molecules together
in a polymer.
2. How does the structure of the phthalic acid molecule change in the esterification reaction?
3. How does the structure of glycerol change?