Effects of weight reduction of packaging material on the mechanical performance of PET bottles for cooking oil

This study compares and evaluates the mechanical performance of two types of PET bottle of different nominal weights but identical design and filled with 900 ml vegetable cooking oil. The air in the headspace of all the bottles was replaced with liquid or gaseous nitrogen upon conclusion of the filling operation and immediately before capping. Two different closures, with an internal or external tamper‐evident feature, were used on the 20 g bottles. The 27 g bottle was closed exclusively with the closure fitted with an external seal. The 20 g PET bottles prior to capping were either flushed with gaseous nitrogen or pressurized with liquid nitrogen. The air contained in the headspace of the 27 g bottle was removed by injection of gaseous nitrogen only. Corrugated fibreboard cases containing 20 bottles each were submitted to a vibration test and all the components of the packaging system were subsequently evaluated with respect to important mechanical properties, such as stacking strength, drop impact strength and package integrity. The results show that the closure with external seal provided considerably better protection against leakage. Also tests conducted with stacks of five corrugated cases each and arranged onto two pallets placed one upon the other demonstrated that reducing total bottle weight by 26% is viable in terms of mechanical performance. On the other hand, the use of pressurized liquid nitrogen was found to be unnecessary. Copyright © 2000 John Wiley & Sons, Ltd.