Practice Problem 2

Atactic polypropylene is a soft, rubbery material with no commercial value. The isotactic polymer is a rigid substance with an excellent resistance to mechanical stress. Explain the difference between the physical properties of these two forms of polypropylene.

Solution

Isotactic polypropylene is easier to pack in a regular fashion than the atactic form of the polymer. As a result, isotactic polypropylene is more crystalline, which makes the solid more rigid.