AN EVALUATION OF ETHYLCELLULOSE-PLASTICIZER INTERACTIONS USING INTRINSIC-VISCOSITY AND INTERACTION CONSTANT

Chemical interactions between ethylcellulose and twelve different pote ntial plasticizers were evaluated using the dilute polymer solution pa rameters, intrinsic viscosity, [eta], and interaction constant, k', de termined using capillary viscometry. The parameters for the polymer we re evaluated for binary solvent systems containing variable amounts of methanol as a cosolvent with each of the plasticizers at the followin g percent weight ratios: 20: 80, 40: 60, 60: 40 and 80: 20. Little dif ference was found among the solvent systems studied for either paramet er though k' was found to be slightly greater than 0.5 indicating that polymer-polymer interactions predominate. It is suggested that this m ethod is not ideally suited for evaluating potential plasticizers for their suitability as film coating additives in ethylcellulose coating systems.