Combined Application of Imaging Methods for the Characterization of a Polymer Blend

Abstract

Morphological studies were performed on a polymer blend, used as a friction bearing, consisting of polyamide 6.6 (80%), poly-(tetrafluoroethylene) (18%), and silicone oil (2%). Raman imaging, FT-IR imaging, scanning electron microscopy with energy-dispersive X-ray spectrometry, and microthermal analysis determined the distribution of poly(tetrafluoroethylene) clusters in the polyamide matrix. Each characterization method allows qualitative identification of the main components and provides information about cluster size and distribution. It is proved that poly(tetrafluoroethylene) clusters of 10 to 30 μm are randomly distributed in a polyamide matrix and that silicone oil can be found at the cluster matrix interface. The good agreement that was obtained in our investigations indicates high reliability of the results since all applied methods are based on different chemical and physical properties. This combined approach revealed information about the morphology of the blend for a better understanding of its working principle and enhanced knowledge for its processing. A comparison of the different methods employed in this study highlights their advantages and limitations for polymer analyses.

Applications of FTIR Spectroscopic Imaging in Pharmaceutical Science

“…Longer wavelengths have greater depth of penetration. The expected depths of penetration using common polymeric materials with refractive indices of around 1.5 are usually in the range 1-5 mm when working in mid-IR [13]. The equation also states that total internal reflection will only occur if the incidence angle is larger than the critical angle.…”

Quantitative spatial distribution of sirolimus and polymers in drug‐eluting stents using confocal Raman microscopy

“…Combining the methods with microscopy has provided the ability to map the distribution of polymer blends, pharmaceutical formulations, and drug-polymer coatings on stents. 11,[15][16][17][23][24][25][26][27][28][29][30] Although NIR and FTIR imaging provide chemical selectivity, both suffer from poor spatial resolution and cannot depth profile through coatings. Fluorescence microscopy requires chemical labeling of the drug or a fluorophore inherent to the system.…”

Experimental Testing of Lateral and Depth Resolution in Imaging Methods

“…For Raman imaging we used the 733 cm À1 line of PTFE as described recently. [1] Comparative images were obtained from that blend by environmental scanning electron microscopy (ESEM). Because of the ESEM advantages (no coating of electrically non-conductive samples necessary) it was possible to image the same area first in ESEM, then in the Raman microscope, and afterwards to repeat that cycle again.…”

“…), thus allowing a mutual testing of the limitations of the individual methods, [1] especially those recently introduced (namely vibrational micro-spectroscopy [2,3] ). The lateral resolution of infrared imaging can be improved by using an ATR objective with a high refractive Germanium crystal.…”