PETpla.net Insider 05 / 2014

22 PET planet insider Vol. 15 No. 05/14 www.petpla.net MATERIAL / RECYCLING Bottles, preforms and closures, part 11 Manufacture and states of PET By Dr Laura Martin, formerly with Husky Injection Molding Systems and Ottmar Brandau, Apex Container Tech Inc. After having gathered some insights into the basics of PET preform design in part 11, we now follow down the road and take a closer look at PET material properties and how they are being influenced during the transformation process from resin pellets to preforms and finished bottles. PETplanet insider is publishing extracts from successive chapters of Ottmar Brandau’s “Bottles, Preforms and Clo- sures”, which was first published by hbmedia. A newly revised version is reissued under the Elsevier imprint. PET belongs to the group of mate- rials known as thermoplastic poly- mers. The application of heat causes the softening and deformation of ther- moplastics. In contrast, thermosets cure or solidify with the application of heat and simply burn with continued heating. Like all polymers, PET is a large molecule consisting of chains of repeating units. The PET used for bot- tles typically has about 100–140 of the repeating unit. A monomer is a single unit that is repeated to form a polymer chain (Greek “mono” one; “meros” part). Polymerisation is the name given