| Abstract: | In the present work, fusion behavior, crystallinity, and mechanical properties of beverage bottle poly(ethylene terephthalate) (PET) was compared with those of the virgin material. Viscosimetry measurements, differential scanning calorimetric studies, impact and tensile determinations were made in both materials. The lower M v of bottle PET revealed that a thermomechanical degradation occurred during processing. Although bottles possess a considerable degree of crystallinity (≈30 percent), the crystallites are so small that they don't scatter light and, therefore, bottles are transparent. Virgin PET exhibited a brittle behavior while bottle PET exhibited a ductile one. This is a consequence of the difference In crystallinity between both materials (greater for virgin PET because of its original higher crystallinity content), although they were molded under the same conditions. Such difference was attributable to a “crystalline memory” effect having its origin in the orientation of the material during Injection molding at low temperature (250°C). Injection-molded PET specimens showed a strong, crystalline memory, capable of crystallization during very fast quenchings. |
