Initial experimental estimation of compatibility

In another method, particles of crystalhne polymer are placed on a microscope glass and moisted with plashcizer. The temperahrre is slowly raised at a rate of 0.5°C/min, the sample is periodicahy photographed, and the voltrme frachon of plasticizer in the swohen parhcles is recorded. At a certain temperahrre the particles change their shape and then melt. The fohowing eqtrahon is used in the interpretation of resrdts  

A large number of theoretical assumptions and the scatter in particle sizes make the usefulness of the method doubtful. The Huggins parameter may also be estimated using data on sedimentation, light scattering, and from inversion gas-liquid chromatography. 

There are several methods for determining the critical temperature of dissolution . Detecting the change in viscosity of dilnted snspensions during temperature rise is one method. The increase in viscosity of the system is caused by dissolution of polymer in the plasticizer. The method is useful only for diluted systems. 

The Brabender plastograph is nsed to measure the work of mixing of a typical formulation. A rapid change in torqne during gel formation results from gelation. This is a typical method used to select the conditions of manufacture for the plasticized compositions. 

Yet another method is based on viscosity measurements of diluted polymer solutions in plasticizers. Good plasticizers cause a more rapid viscosity increase as the concentration of polymer in solution increases. 

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