Question

why borax activates pva

Answer 1

A solution of PVA can be made into a slime by adding borax solution, which creates cross-links between polymer chains.

Answer 2

A polyvinyl alcohol solution can be made by adding a slime solution into borax.

The reason why it activates polyvinyl alcohol is that borax can construct cross-links between the polymers.

Everything in the answer becomes well firmed and fixed when Borax is added.

This is commonly used in the present day world.