bioplasticsMAGAZINE_0904

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