A simple activity to help students understand how absorbent polymers are used in nappies.

See also The Design of Nappies

 

PRACTICAL: Nappy dissection

AIM: To investigate the nature of absorbent nappies.

 

Theory:  Manufacturers place a water absorbing polymer into the cotton padding of nappies.

METHOD AND RESULTS:

  • Wear safety googles and avoid contact with eyes.
  • Open a sheet of newspaper on a table top
  • Cut away the nappy lining to reveal the padding
  • Carefully rub sections of the padding onto the newspaper. This will cause the polymer crystals to fall onto the newspaper.

(Note: The crystals look like salt.)

  • Discard any cotton and carefully pour the polymer into 50 mL of water.
  • Stir the mixture
  • Discard the cotton padding and nappy lining into the newspaper, then into the bin. Do not place materials into the sink.

Safety: The small polymer crystals can absorbs many times their own weight in water. Avoid contact with the eyes and do not ingest.

 

Describe the material

 

 

  • Add a small amount of salt to the mixture

Describe what happens

 

 

 

CONCLUSION:

  •  Describe the properties of the polymer used in absorbent nappies.

 

 

  •  Why do manufactures place excess absorbent polymer in nappies?

 Hint: Urine contains salt.

 

 

  •  How do manufactures make super absorbent nappies?

 

Molar Mass