Masterbatches offer an inexpensive opportunity for dyeing plastics during the manufacturing process or to influence various properties of the basic plastic. Measurements of masterbatches with the handheld Raman spectrometer Mira M-1 require no sample preparation and provide immediate results that identify the masterbatches unambiguously, no matter whether they are intended for dyeing or for modifying the basic plastic.

All spectra were measured using the Mira M-1 handheld Raman spectrometer in auto-acquisition mode, i.e., integration times were determined automatically. A laser wavelength of 785 nm and the Orbital-Raster-Scan (ORS) technique were used. Some of the color masterbatches were filled into vials and analyzed using the vial holder attachment, while other samples were analyzed directly in their plastic container using the long working distance (LWD) lens.

The following samples were used in this study:

To build the library, the samples were measured in vials. Using the Mira Cal software, a qualitative differentiation of the spectra was achieved (see Figure 2), although the two black samples PE 3208 and RE 32126 could not be analyzed, because the laser light was absorbed completely.

When using Mira in its autonomous mode, i.e., without the use of the Mira Cal software, secure identification of the masterbatches was also achieved. However, small influences of the plastic container of the masterbatch were observed.