DIFFUSION OF DYES IN POLYCARBONATE - A NEW MEASUREMENT TECHNIQUE AND CORRELATION WITH SHADOW AREAS

Using a simple but novel technique, we have examined diffusion of an assortment of dyes in polycarbonate above its T(g) (180.0-degrees-C). The procedure yields precise diffusion constants at dye concentrations approximating infinite dilution. Our initial attempts to obtain a Quantitative Structure Activity Relationship (QSAR) between the measured diffusion constants and properties calculated for MOPAC optimized dye structures were unsuccessful. However, elongating or streamlining the structures yields a remarkably good QSAR with a single parameter, the log of the shadow area cast down the dye's long axis.