Fig. 4

PS penetration curves for (a) Na+and (b) Ca2+. O3-aged PS penetration curve for (c) Na+ and (d) Ca2+. UV-aged PS penetration curve for (e) Na+ and (f) Ca2+.

PS penetration curves for (a) Na+and (b) Ca2+. O3-aged PS penetration curve for (c) Na+ and (d) Ca2+. UV-aged PS penetration curve for (e) Na+ and (f) Ca2+.