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Name: Nicole
Status: other
Grade: N/A
Location: IL
Country: N/A
Date: April 2006

Question:
When I make borax and glue slime with students, I explain that the sodium borate from the borax acts as a crosslinker to link the chains of polyvinyl alcohol together, resulting in a big gooey mass of slime. I recently read the Elmer's glue contains 2 polymers - polyvinyl alcohol and polyvinyl acetate. When I make slime with borax and Elmer's, am I linking the polyvinyl alcohol strands or the polyvinyl acetate strands - or both? Help! I want to make sure I'm presenting an accurate explanation to my students.



Replies:
The crosslinking with Elmer's Glue is primarily with the polyvinyl alcohol. However, it may be a bit more complicated in its details. The polymers is Elmer's Glue may be a copolymer of polyvinyl alcohol and polyvinyl acetate, in which case the co-monomer polyvinyl alcohol can participate in the crosslinking with borax. In addition, polyvinyl acetate reacts with water (slowly) producing acetic acid and a hydroxyl group remaining in the polymer backbone, especially if the Elmer's Glue is old. In this case the hydroxyl group could also crosslink with the borax. The fundamental reaction is between the hydroxyl group and the boric acid from the borax, whatever the source of the hydroxyl group. Elmer's Glue is a much more clever product than most people think, so you are wise to want to be accurate in your explanation.

Vince Calder



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