Transmission FT-IR Imaging

Polymer blends of PHB and PLA have previously been analyzed with miscellaneous methods by several other groups [49-51]. In the following, the used of transmission FT-IR imaging will be demonstrated as an alternative approach towards a better understanding of the chemical and physical properties of these materials. 

One of the fields of polymer science for which FT-IR imaging has proved of extraordinary importance in terms of scientific and practical aspects is the analysis of phase separation in polymer blends. Blending of different polymers is a Ifequently used technique in industrial polymer production to optimize the material projrerties. As pointed out in Chapter 5.01, the mechanical properties of PHB can be enhanced by blending with FLA. For the preparation of the optimum blend, it has to be taken into account that the miscibility of different polymers depends on their concentration, the temperature, and their stmaural characteristics. Polymer blends of PHB and PLA have previously been analyzed with miscellaneous methods by several other researchers and in what follows the application of transmission FT-IR imaging will be demonstrated as an alternative approach toward a better tmderstanding of their chemical and physical properties. 

The main research activities using a FPA detector for FT-IR imaging began in 1997, since when the group of Koenig, at Case Western Reserve University in Cleveland, USA, has made important contributions to this research area. In their first FT-IR imaging applications in the transmission mode (1996, 1998, 1999), the group studied the diffusion of liquid crystals into polymers. The diffusion process was analyzed in detail and quantitative results, such as diffusion coefficients, were derived [2-4]. 

Chan and Kazarian were able to achieve a spatial resolution of 3-4 xm with micro ATR FT-IR imaging measurements with a Ge ATR crystal [37]. A recent report by Lasch and Naumann described the lateral resolution of FT-IR imaging measurements in transmission, whereby numerous results from measurements of a resolution target USAF 1951 and tissue samples with different imaging systems from different manufacturers and with different objectives were compared [41]. 

The Test Systems In order to demonstrate the spatial resolution achieved in practical measurements, two test sample systems were investigated by FT-IR imaging measurements in the ATR mode and in transmission. The sizes of the imaging areas were 50 X 50 pm for the micro ATR FT-IR measurements (20x objective) and 260x260pm for the micro FT-IR transmission measurements (15x objective). 

Figures 9.16 and 9.17 show graphs of the integral absorbance of PE and PC (FT-IR/ATR imaging measurement) and of PC (FT-IR imaging measurement in transmission) versus pixel number of a row (64 pixels) perpendicular to the PE/PC borderline between the laminate (PE/PC) and the single layer (PE) (50 pm and 260pm, respectively). The integral absorbances used for the calculation of the spatial resolution at 95% and 5% of the maximum integral absorbance (100%) are marked.

The FT-IR transmission spectra of the individual blend components PHB and PLA and of a PHB/PLA (50 50wt%) blend film are shown in Figure 9.21a and b, respectively. In Figure 9.21a, only a limited number of absorption bands are detectable which are specific for the individual blend components PHB and PLA. For FT-IR imaging, primarily the nonoverlapped left and right wings of the intense... 

Fig. 32 Comparison of XPS Cl 2p and transmission FT-IR PVC (1333 cm ) images for a PVC/PMMA (25/75) blend. (Reprinted with permission from [226]. Copyright 2000 Society for Applied Spectroscopy)...

X-ray diffraction analysis (XRD) Fourier transform infrared spectroscopy (FT-IR, FT-IR image) Thermogravimetric analysis (TGA), differential thermal analysis (DTA) Mossbauer spectroscopy Light microscopy Transmission electron microscopy (TEM)... 

Figure 8.16 Graph of the integral absorbance of PC (FT-IR imaging measurement in transmission) versus pixel number of a row (64 pixel) perpendicular to the PE/PC borderline (260 pm, 4.06 pm/pixel). The...

FT-IR Imaging in ATR and Transmission Modes Practical Considerations and Emerging Applications... 

In this chapter, we describe some general principles and applications of FT-IR imaging in ATR and transmission mode with a focus on technical considerations, new developments, and emerging applications. 

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