Rational design of stretched plastic packaging
Careful scientific development of new packaging products and processing procedures based on the relationship between the structure of polymers and their resulting properties is lacking. European researchers seeking to develop a global strategy for scientific optimisation of stretched plastic packaging initiated the ‘Advanced knowledge of polymer deformation for tomorrow's packaging’ (APT_PACK) project. Scientists focused on three types of polymers relevant to stretched plastic packaging (amorphous, semi-crystalline and amorphous that crystallises during forming) and the two conventional processing methods, thermoforming and stretch blow moulding. They sought to elucidate correlations between polymer structures and end-use properties. Thus, they studied evolution of microstructure during processing with a special focus on the rheology (flow properties) of the polymers. Experimentally, scientists developed high-velocity loading tests for thermoforming and stretch blow moulding. They advanced knowledge related to microstructure development as well as heating, stretching and cooling. Results contributed to the formation of a database on heating, thermal contact, loading histories and friction during processing. Data has helped to define and propose relevant models as well as focus future numerical codes for rational design. Overall, APT-PACK advanced scientific knowledge and understanding of the correlation among polymer materials, processing methods and conditions, and final end-user product properties that should advance the global stretched plastic packaging market.
