Re: Making plastic from milk?

Let me start of by saying plastics are polymers, so that when I refer to polymers in my answers, plastics fall under that category.

Milk contains a protein called casein. Proteins are complex polypeptide copolymers formed by the condensation reactions of amino acids.(Reference: Contemporary Polymer Chemistry, H.R. Allcock and F.W. Lampe, 1990, pg. 169) Plastics and fibers have been manufactured from regenerated protein from a number of sources including milk. (reference: Polymer Chemistry, M.P. Stevens, 1999, pg.502)

Vinegar is an acid. When any acid is added to milk, the casein separates out as curd. So by the addition of vinegar, the casein, in the form of curd, separates out and falls to the bottom as long strands (i.e., polymers).

The definition of casein is a white, tasteless, odorless milk and cheese protein used to make plastics, adhesives, paints and foods.

Based on this evidence, your daughter was separating the casein. This casein is a polymer, so your daughter was separating the polymer from the milk. In my opinion, your daughter did produce a polymer. Though cheese also contains proteins (polymers), so even if your daugther was making cheese, there is still polymer present.

Hope this helps.