Sorting Plastics with Light

Aug-25-14 A new technology able to automatically identify different type of plastic could significantly speed up the sorting process while also reducing instances of human error.

Developed by a team from Ludwig Maximilians Universitat in Munich, the system identifies the plastic types by exposing the pieces to a flash of light, which causes them to fluoresce. That light is then read by photoelectric sensors, which measure how long it takes the fluorescent light to fade. Since the polymer materials used to make plastic items have specific fluorescence lifetimes, the plastic type can be identified by its decay curve. According to lead professor Heinz Langhals: “With this process, errors in measurement are practically ruled out; for any given material, one will always obtain the same value for the fluorescence half-life, just as in the case of radioactive decay.”

Image: Hans Braxmeier

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[GIZMAG.COM]
[EN.UNI-MUENCHEN.DE]

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