Mineral-filled polymer articles and methods of forming same

A method of forming a polymeric article, comprising:

• providing a polymer composition comprising a crystallizable polymer, a mineral filler comprising talc in an amount of more than about 15 wt-% based on the total weight of the polymer composition, and an impact modifier, wherein the crystallizable polymer comprises non-nucleated poly(ethylene terephthalate) (PET), and the polymer composition is at a temperature less than a crystallization temperature of the crystallizable polymer;
• extruding the polymer composition into an extruded sheet with the polymer composition in an amorphous state;
• disposing the extruded sheet of polymer composition in the amorphous state in a mold, wherein the mold has a mold surface with at least a region of the mold surface heated to a temperature of between about 250° F. and about 400° F.;
• thermoforming the extruded sheet of the polymer composition into a polymeric article within the mold;
• retaining the polymeric article in the mold a sufficient time for the crystallizable polymer proximate the heated region of the mold surface to crystallize to a degree of crystallinity of at least about 25%;
• and
• releasing the polymeric article from the mold,
• wherein the crystallizable polymer proximate the heated region of the mold surface is capable of being crystallized to a degree of crystallinity of at least about 25% within 3 seconds.