Fig 3: Sheet samples: (Left Sample – Using rPET Control Flake; Middle & Right Samples – Using rPET Test Flake) CIELab, 10 degrees, D65 90 80 70 60 50 40 30 20 10 rPET control rPET test (w/ PLA) 50/50 blend commercial sheet extrusion line. The control and test rPET flake was dried normally at typical PET conditions and no drying problems were noted by the sheet manufacturer. At the beginning of the run, sheet was made first using the rPET control flake (70% rPET control flake/30% virgin PET). Right after, and without stopping the extrusion process, sheet was then produced using the rPET test flake (70% rPET test flake/30% virgin PET representing a PLA bottle flake content of 317 ppm). Samples were taken over the course of the run (6 hrs.) for color and haze analysis. 0 -10 White-Black Scale Green-Red Scale Yellow-Blue Scale Haziness Table 2: 3mm Lab Plaque Color and Haze Comparison In order to compare the commercial sheet samples an independent testing laboratory was engaged. Clean flake from both the rPET control and rPET test material was provided to Plastic Forming Enterprise (PFE) from the sheet manufacturer. PFE, a third-party plastics and recycling test lab, produced and analyzed 3 mm plaque samples made from the rPET control and test flake. PFE’s analysis concluded there was no appreciable color or haze difference between the rPET control and rPET test plaque samples [Table 2]. Also, there was no appreciable color or haze difference throughout the 6 hour course of the commercial sheet run. For all commercial intents, the rPET sheets were identical and both sold successfully in the end market. Conclusion Reflectance Nanomenters PET PLA The study showed that PLA can automatically be sorted from PET using Near Infrared (NIR) technology down to very low levels. (only 453 ppm PLA bottles entered the recycling stream after NIR sorting). This amount does not result in any measurable effects for the recycled PET. These results compare favorably with TiTech’s NIR sorting claims of high purity (up to 98%) and efficiency (up to 95%) using their technology. The findings of this field test should help pave the way for further market development. Fig 4: Schematic of a typical NIR-Spectrum, PLA and PET peaks clearly distinguishable www.natureworksllc.com www.titech.com www.primowater.com 26 bioplastics MAGAZINE [04/09] Vol. 4
2 nd PLA Bottle Conference 14-16 September 2009 Munich, Germany | Holiday Inn City Centre within the Supporting Programme of Organized by PLA, a ‘green’ alternative for PET? PLA for hot-fill applications? Barrier enhancement for PLA bottles? End-of-Life Options for PLA bottles? Automatic sorting of PLA / PET? Experiences from bottlers using PLA? Want to hear more about these topics? All these subjects and many more such as labels and caps, additives and colorants, challenges and opportunities … are being openly discussed at the 2 nd PLA Bottle Conference. Visit www.pla-bottle-conference.com to see the programme and to register.