In PET packaging, manufacturers often face a tough choice: achieving strong mechanical, thermal, and barrier properties requires crystallinity — but crystallinity also reduces transparency. On the other hand, fully amorphous PET is perfectly clear but lacks the needed performance. But what if this trade-off wasn’t necessary? What if one could control PET’s crystallisation to get both: top performance and clarity?
To start with — crystallisation in PET can proceed via fundamentally different mechanisms: quiescent crystallisation and Flow-Enhanced Nucleation and Induced Crystallisation (FENIC), among others.
The FENIC mechanism is typically overlooked — and, importantly, is often mistaken for quiescent crystallisation in the context of PET processing. Quiescent crystallisation is a well-documented and mostly unwanted phenomenon in industrial processing. It refers to the process where a polymer transitions from an amorphous to a crystalline state under static, non-deformational conditions, typically influenced by thermal treatments and the polymer's thermal history.1 In contrast, FENIC actively uses flow to enhance nucleation and drive crystallisation and is governed and controlled through the science of rheology. So, although scientifically understood and well-described, the opportunities resulting from FENIC are still largely unknown to the broader packaging supply chain. 2
At Keiryo Packaging, we are pioneering an approach to actively harness FENIC, unlocking new performance advantages for (amongst others) PET packaging. This is built on the fundamental principle that “performance follows morphology.” By steering the morphological composition on the processing level, we can achieve tailored properties that directly benefit the final PET packaging performance.
FENIC is applicable to all types of semi-crystalline polymers, whether from fossil or (partial) bio-based origin.
