DYE DIFFUSION IN POLYCARBONATE IN THE PRESENCE OF ADDITIVES

The tracer diffusion coefficient of the photoproduct of camphorquinone (CQ) in polycarbonate (PC) is measured as a function of temperature and additive concentration. The additives are dioctyl phthalate and 1,3- and 1,4-dichlorobenzene. The effects of polymer molecule weight distribution and the presence of plasticizer molecules on the tracer diffusion coefficient are investigated. In the nearly mono-disperse PC or PC containing no plasticizer, the diffusion coefficient precipitously decreases as the sample temperature is lowered toward T(g). The rapid decrease of the diffusion coefficient in the vicinity of T(g) is, however, not observed in the plasticized PC. Empirical equations based on free volume theory are developed to describe the temperature and concentration dependence of the tracer diffusion coefficient.