Michel Anna P M, Morrison Alexandra E, Colson Beckett C, Pardis William A, Moya Xavier A, Harb Charles C, White Helen K
Opt Express. 2020 Jun 8;28(12):17741-17756. doi: 10.1364/OE.393231.
The identification of plastic type is important for environmental applications ranging from recycling to understanding the fate of plastics in marine, atmospheric, and terrestrial environments. Infrared reflectance spectroscopy is a powerful approach for plastics identification, requiring only optical access to a sample. The use of visible and near-infrared wavelengths for plastics identification are limiting as dark colored plastics absorb at these wavelengths, producing no reflectance spectra. The use of mid-infrared wavelengths instead enables dark plastics to be identified. Here we demonstrate the capability to utilize a pulsed, widely-tunable (5.59 - 7.41 µm) mid-infrared quantum cascade laser, as the source for reflectance spectroscopy, for the rapid and robust identification of plastics. Through the application of linear discriminant analysis to the resulting spectral data set, we demonstrate that we can correctly classify five plastic types: polyethylene terephthalate (PET), high density polyethylene (HDPE), low density polyethylene (LDPE), polypropylene (PP), and polystyrene (PS), with a 97% accuracy rate.
塑料类型的识别对于从回收利用到了解塑料在海洋、大气和陆地环境中的归宿等环境应用至关重要。红外反射光谱法是一种用于塑料识别的强大方法，只需要对样品进行光学检测。使用可见光和近红外波长进行塑料识别存在局限性，因为深色塑料会在这些波长下吸收，无法产生反射光谱。而使用中红外波长则能够识别深色塑料。在此，我们展示了利用脉冲、宽可调谐（5.59 - 7.41 µm）的中红外量子级联激光器作为反射光谱的光源，对塑料进行快速且可靠识别的能力。通过将线性判别分析应用于所得光谱数据集，我们证明能够以97%的准确率正确分类五种塑料类型：聚对苯二甲酸乙二酯（PET）、高密度聚乙烯（HDPE）、低密度聚乙烯（LDPE）、聚丙烯（PP）和聚苯乙烯（PS）。
