22 NIR Imaging
531
Fig. 22.12 Change in skewness according to the increase of defective area in the tablet. Copyright
(2019) IM publication
22.5.2 Biodegradable Polymer Evaluation [29, 30]
As examples of quantitative analysis of crystallinity of biodegradable polymers,
polylactic acid (PLA) and the effect of its concentration in PLA/poly-(R)-3hydroxybutyrate (PHB) blends were investigated using the previously described
Compovision system. PLA samples with different crystallinity and blended sample
of PLA/PHB were prepared, and NIR spectral images in the 1000–2350 nm region
were obtained for a spatial region of 150 × 200 mm area (with 0.25 mm spatial resolution). Application of the standard normal variate (SNV) pretreatment to collected
spectra followed by partial least squares regression enabled prediction of crystallinity
and concentration of PLA in the biopolymer blend. Figure 22.14 depicts NIR images
of wide-area crystal evolution of PLA. Note that the PLA plate was subjected to
gradual temperature slope in the range 70–105 °C. A SNV-based prediction image
gave an obvious contrast of the crystallinity around the crystal growth area according
to slight temperature change. Moreover, it clarified the inhomogeneity of crystal
evolution over the sample area.
531
Fig. 22.12 Change in skewness according to the increase of defective area in the tablet. Copyright
(2019) IM publication
22.5.2 Biodegradable Polymer Evaluation [29, 30]
As examples of quantitative analysis of crystallinity of biodegradable polymers,
polylactic acid (PLA) and the effect of its concentration in PLA/poly-(R)-3hydroxybutyrate (PHB) blends were investigated using the previously described
Compovision system. PLA samples with different crystallinity and blended sample
of PLA/PHB were prepared, and NIR spectral images in the 1000–2350 nm region
were obtained for a spatial region of 150 × 200 mm area (with 0.25 mm spatial resolution). Application of the standard normal variate (SNV) pretreatment to collected
spectra followed by partial least squares regression enabled prediction of crystallinity
and concentration of PLA in the biopolymer blend. Figure 22.14 depicts NIR images
of wide-area crystal evolution of PLA. Note that the PLA plate was subjected to
gradual temperature slope in the range 70–105 °C. A SNV-based prediction image
gave an obvious contrast of the crystallinity around the crystal growth area according
to slight temperature change. Moreover, it clarified the inhomogeneity of crystal
evolution over the sample area.