Chitosan fibers enhanced gellan gum hydrogels with superior mechanical properties and water-holding capacity

New hydrogels based on acetylated gellan gum (A-gellan) and chitosan fibers (F-chitosan) are prepared and coded as F-chitosan/A-gellan. Compared to A-gellan hydrogel, F-chitosan/A-gellan hydrogels show higher storage moduli and water-holding capacity. Specifically, the storage modulus of 2.0 F-chitosan/A-gellan (mass ratio of chitosan fibers and gellan gum is 2:1) hydrogels at regular frequency of 1 rad/s is 2.2 kPa, approximately 4.6 times more than that of the A-gellan hydrogel. In addition, the fractural morphology analysis of A-gellan and 2.0 F-chitosan/A-gellan hydrogels treated by different dry methods indicates that the 2.0 F-chitosan/A-gellan hydrogel has more stable macrostructure. Moreover, compared to A-gellan gel, 2.0 F-chitosan/A-gellan gel shows higher activation energy and water-holding capacity during dehydration and higher dielectric constant after dehydration. These results can be attributed to the special advantages of chitosan fibers, which are full of polar and hydrophilic amino group and can transfer the load applied on the hydrogels in fiber form. (C) 2013 Elsevier Ltd. All rights reserved.