Crystallinity and material distribution management in optimizing PET bottle performance

At the ABC conference, held recently in Pittsburgh, PA, Georg Wolfe, Agr’s Chief Technical Officer, provided an update on the continued progress his team is making with regards to bottle performance optimization through the management of material distribution and orientation (crystallinity). In his presentation, he detailed the results from extensive studies that his team has done on the relationships that affect the crystalline structure of PET bottles as they are produced, using both hot and chilled mold production processes.

“The experiments and extensive knowledge base created over the last two years of our research and development effort has proven enlightening,” cited Mr. Wolfe.  He further explained what optimizing orientation means to bottle manufacturers and fillers:  A highly oriented container will have the best possible stress crack performance, minimum volume expansion under pressure, and maximum shelf-life and burst pressure.  In addition, for the cold mold process, it is possible to realize a reduction in oven temperatures greater than several degrees C .  This energy savings can be significant.

For hot-mold processing, dimensional and volumetric stability is paramount. Optimizing crystallinity in production applications using the various hot-mold technologies is essential to maintain dimensional and volumetric integrity and stability through the hot fill process.

Data from these experiments (DOE) are the foundation for the sophisticated blowmolder control algorithms that are being incorporated into a commercial product to actively manage crystallinity within the reheat/stretch-blow process. According to Mr. Wolfe, Agr intends to commercialize the process for crystallinity/orientation optimization under the trade name CrystalView™.  This product, when coupled with Agr’s Process Pilot automated blowmolder management system will make it possible to process stronger, better performing containers plus provide the added capability for bottle producers to further light-weight with minimal risk. “If you can actively manage crystallinity and at the same time control thickness, you have much greater control over the bottle attributes that affect performance, especially with very light bottles,” concluded Mr. Wolfe.

The CrystalView product is currently undergoing beta tests at several US sites.  It is expected to be available to the market in the early part of 2016.