A STUDY OF THE DEPENDENCE OF THE BULK ETCH RATE AND THE REDUCED ETCH RATE ON THE CONCENTRATION OF ETCHED PRODUCTS OF LEXAN

Measurements of the bulk etch rate, upsilon(g), for etching solutions with concentrations of Lexan etched products, x, ranging from 0 to 7.8 g/l showed the existence of an initial region where upsilon(g) increases with x; and a second region, for concentrations above approximately 2.15 g/l, where upsilon(g) no longer depends on x. The division between these two regions (congruent-to 2.15 g/1) did not coincide with the concentration of solubility saturation, found to be at 1.51 g/l. Tracks from relativistic gold ions (with kinetic energies between 10.3 and 10.6 GeV/u) were used to measure the reduced etch rate (S, the ratio between the track etch rate, upsilon(t), and upsilon(g) for three etching solutions with different concentrations of etched products (0.052, 1.81 and 7.8 g/1); the values obtained for the first two concentrations were compatible with each other (3.95 +/- 0.16 and 3.85 +/- 0.14), whereas the reduced etch rate corresponding to the concentration of 7.8 g/l of etched products was significantly different; 4.68 +/- 0.14.