Lecture
I. Depolymerization of Polymethyl Methacrylate
Place a sample of finely ground polymer in a test tube and heat it in the flame of an alcohol lamp until white vapors appear above the surface of the molten substance. Cool the test tube. After cooling, add 1–2 cm3 of iodine solution. Decolorization occurs. Write the equations of the reactions taking place, given that polymethyl methacrylate — is the polymerization product of the methyl ester of 2-methylpropenoic acid.
II. Properties of Polymers
1. Using a test-tube holder, gently heat pieces of kapron and lavsan articles over the flame of an alcohol lamp. When the polymer becomes viscous-fluid, touch it with a splint or a glass rod and, drawing it away to the side, pull out a thin fiber. What property of polymers was manifested in this case?
2. Place pieces of synthetic, man-made, and natural fibers (kapron, lavsan, wool, acetate silk, cotton) into test tubes with solutions of sulfuric acid and alkali. Which reagents destroy the indicated polymers and why? How does acetone act on acetate fiber?
3. Place pieces of polymer materials into the flame of an alcohol lamp. Note the character of the flame (whether they burn or do not burn outside the flame) and the type of combustion products.
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