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Slime

Chemicals and Solutions

  • 4% Sodium borate in water
  • 4% Polyvinyl alcohol in water

Materials

  • 25mL graduated cylinder
  • 10mL graduated cylinder
  • 3oz cups
  • Stir sticks
  • Optional: food coloring

Procedure

  • Mix 25 ml polyvinyl alcohol solution with 5 ml sodium borate solution and a few drops of food coloring.
  • Stir to make the polymer.

Discussion

Borate ion crosslinks with the hydroxyl group of polyvinyl alcohol. These crosslinks probably involve multiple hydrogen bonds that break and reform. The relatively weak crosslinking is necessary to produce the viscoelastic gel. Slime is a non-Newtonian fluid that is dilatant, that is, under stress, the material dilates or expands. Other stress thickening materials are quicksand and Silly Putty. Under low stress, such as pulling slowly, dilatant materials will flow and stretch; if tossed gently they will bounce. Under high stress, such as pulling sharply, dilatant materials break.

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