Water Absorption

Tables 1 and 2 (last row) show the results of water absorption at the equilibrium for PET fabrics coated with hydrogel by the photochemical method and by gamma irradiation. All samples absorbed water in relatively high values (roughly 2 times their weight). It can be recognized that increased crosslinker content resulted in a lower water absorption, while increasing the PEGMA content resulted in higher water absorption for the hydrogel coatings prepared by the photochemical method (Table 1). In the case of hydrogel coatings prepared by gamma irradiation, the effect of increased water absorption due to the increased PEGMA content was also observed, however the sample prepared without PEGMA also showed a relatively high water absorption (Table 2). Since the crosslinking in the latter case is induced by the gamma rays (no chemical crosslinker added), it is possible that coatings without PEGMA resulted in lower crosslinking degree (higher water absorption). The effect of the coating thickness on water absorption was eliminated by subtracting the PET fabric weight in each case, see experimental section Equation (2).
