Chemical Meaning of Near Infrared Spectra from a Portable Near Infrared Spectrometer for Various Plastic Wastes

Abstract

We examined NIR spectra obtained from various plastic wastes using a portable near infrared spectrometer;herein, we discuss chemical implications of spectral characteristics. A barcode spectrum derivedfrom the second-order derivatives spectrum provides effective alternatives to discriminate plastic types. Principal component analysis, which is applied to barcode spectra, reveals characteristics and similarity of NIR spectra among plastic samples. Chemical structure of plastic samples reflects NIR spectra. Spectral differencescan be explained with reference to whether the plastic has some functional group (aromatic CH, COand Cl) or not.