NIR Discrimination of Thermoplastic Resins

October 2, 2005

Analytical Spectral Devices, Inc.

ASD's NIR technology can be used to qualitatively distinguish between various thermoplastic resins.

With plastics pervading virtually every aspect of manufacturing (from appliances to apparel), the need to refine products and processes becomes increasingly significant. To those ends, this study purposes to use NIR technology to qualitatively pinpoint the differences between thermoplastic resins

Spectra were obtained using ASD's LabSpec®Pro and High Intensity Source Probe (Muglight). The baseline (or reference standard) was derived using Spectralon — a commercially available polytetrafluoroethylene with a nearly 100% reflective surface across the entire NIR region. The resins were then placed in the sample puck on the sapphire window of the Muglight and measurements recorded.

Figure 1. Spectrometric difference between six different resins.

The sample spectra were collected using LOG 1/Reflectance — a math pretreatment commonly used for linearizing reflectance data. Six different thermoplastic resins (described below) were acquired. Applying the full-range wavelength (350 nm to 2500 nm) with ten spectra averaging, were gathered for each of the following samples:

1. ABS Terluran GP22 uncolored

2. ABS Terluran EGP07 natural

3. ABS Terluran GP35 uncolored

4. ABS Terluran HH112 natural

5. ABS Terluran HI 10 natural

6. ABS Terluran EHI-5 natural

Figure 2. Difference occurring between 1700 nm and 2300 nm.

The chemometric software Grams 32/Al™ version was employed to compile all spectra and correlating data points (the data was calculated via Grams discriminate mode). Using cross-validation and self-prediction methodologies, an effective calibration model was achieved. Analysis of the data shows that an accurate model was successfully generated for predicting quantification of thermoplastic resins. As confirmed by these findings, ASD's NIR technology can be readily adapted to qualitatively distinguish between various thermoplastic resins.

Analytical Spectral Devices, Inc.

5335 Sterling Drive, Suite A, Boulder, Colorado 80301

Tel. (303) 444-6522