At K 2013, Georg Wolfe, Agr's chief technical officer, talked to PlasticsToday about a recent presentation he gave at the PETnology Conference. A key point of the presentation was the emphasis on crystallinity levels in PET bottles.
In his presentation, Wolfe detailed the reheat stretch blow process and illustrated how certain factors affected crystallinity levels of a finished bottle. Some of the key findings included the management of preform energy distribution during the heating process has a significant effect on crystallinity levels as well as material distribution.
These findings are a result of a series of experiments (DOE) that were structured to gain a statistical understanding of the relationships between preform and mold temperature (energy), the resulting container crystallinity and its effects on container performance. The results of the experiment showed that across a broad range of container mold processing temperatures, crystallinity is closely linked to preform energy levels and, in conclusion, can be actively managed by adjusting the preform temperature set point.