This is my fourteenth science project. It is about cross-linking and polymers.

Objective: Explore the chemical reaction between Elmer's glue and liquid laundry starch that changes the properties of two polymers by the formation of cross-links.

Predictions:

The glue feels sticky and gooey and so I will not be able to roll it into a ball.

The laundry starch feels wet, gooey, sticky, and slightly thick.

I think that if you added laundry starch to glue it would make a gelatinous goo.

After this, I think the glue would feel different.

I think that if you added glue to laundry starch it would make a blueish gelatinous goo.

After this, I think the laundry starch would feel different.

Observations:

The starch and glue took a long time and a lot of mixing to get the mixture to become a ball.

Results:

I observed that when the starch and the glue were mixed together they made a mound.

I observed that the mixture of starch and glue changed as it was mixed together.

I observed that the mixture felt thick and sticky. I also observed that it could be rolled into a mound.

I think this meant that there was a reaction between the glue and the starch because it became warmer, stickier, and thicker than it had been before it was mixed.

Conclusion:

If the polymers, which are long chains of molecules, in a mixture are not cross-linked (connected), they will slide past each other. If they are cross-linked, they will not slide past each other. 

After a lot of work with mixing the of liquid glue and liquid laundry starch, I observed that the substances made a mound because the polymers partially cross-linked. A ball would   have been created if the polymers had completely cross-linked.