A thermoformed polypropylene article, or sheet for preparing such
articles, is formed from a layer of substantially syndiotactic
polypropylene and a thin outer layer of substantially isotactic
polypropylene that is joined to the layer of syndiotactic polypropylene.
At least one of the layers is a non-oriented layer. Two layers of
isotactic polypropylene may be used with the layer of syndiotactic
polypropylene, so that the syndiotactic polypropylene is sandwiched
between the two layers of isotactic polypropylene. The use of the
isotactic polypropylene enhances the processability of the syndiotactic
polypropylene, which is oftentimes difficult to process because of its
lower melting point and slow solidification rate. Because the sheet is
comprised predominantly of syndiotactic polypropylene, utilizing only
thin outer layers of isotactic polypropylene, it has better transparency
and higher impact strength than those conventional articles formed
entirely of isotactic polypropylene.