May 14, 2008 - PET is separated from HDPE and other petroleum-based plastics by floatation. Most biobased plastics also float, however, making the separation of PET from biobased plastics using floatation technology impossible. Because biobased plastics melt at a temperature that is much lower than the melting temperature of PET, the biobased plastics tend to melt in the PET dryers.