Effect of metal temperature on the short contact time adhesion of molten poly(ethylene terephthalate)

This study focused on the effect of metal temperature on the short contact time (few milliseconds) adhesiveness of a molten poly(ethylene terephthalate) (PET) cylinder. Although such a short contact time is typical for PET cylinder handling during preform compression molding (an innovative technique which has many advantages over injection molding, such as higher sustainability, owing to the lower energy and raw material consumption), this type of PET–metal contact has not been examined in the literature. Therefore, a new experiment was designed to test two different metals: stainless steel (AISI 316) and an aluminum alloy (EN AW-6082-T6). Both metal surfaces were finished to achieve nearly identical roughness and morphology as measured by profilometers, while their contact angles were determined according to previous studies. Afterwards, a series of tests including more than 300 single contacts were performed to monitor several parameters affecting PET adhesiveness. The obtained results revealed that the two tested materials exhibited different properties and suggested a probable short contact time adhesion mechanism. This study may be used as reference in the selection of appropriate materials and temperature for molten PET cylinder handling tools. Moreover, since the described phenomenon was previously unknown to the scientific community, this research could be useful in many other research and industrial fields.