Analytical ultracentrifuges with multiplexer and video systems for measuring particle size and molecular mass distributions
The significance of the analytical ultracentrifuge for industrial research has certainly not decreased; it is still an important instrument for controling the production of aqueous as well as organic emulsion polymers, and for the development and analysis of macromolecules. In order to meet increasing demands with respect to the number of samples and of research problems the use of multiple place rotors and of multiplexer systems has become necessary. The use of a homemade multiplexer system for measuring particle size distributions will be demonstrated by some examples. Furthermore, the conventional Schlieren camera was replaced by a pulsed video camera. Thereby, the simultaneous detection of the Schlieren images of up to six polymer solutions has become possible. Controlling the camera and evaluating the video images is done with a personal computer, and the MMD is calculated on a VAX host computer. Finally, a small but significant improvement of the UV system of the Beckman E allows for more reliable scanner measurements with synthetic polymers, as was successfully tested with PMMA samples. For measurements of MMDs the UV system may replace or complement the Schlieren optics.
Key wordsAnalytical ultracentrifuge particle size distribution molecular mass distribution digital image processing UV scanner
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