Effect of freeze-thaw processes on the water-absorption ability and mechanical properties of hydrogel pads with chitosan/poly(vinyl alcohol) based on citrate crosslinks.

In this study, the effect of freeze-thaw (F-T) processes on the mechanical and water absorption performance of citrate cross-linked chitosan/poly(vinyl alcohol) hydrogel pads was evaluated. An excellent cross-linking of 4 % (w/w) citrate was indicated by enhanced peak strength in Fourier-transform infrared spectroscopy and X-ray diffraction patterns, which was applied to the subsequent F-T process. The results in the deswelling rate, water contact angle, and relaxation time of samples exhibited a tendency to decrease and then increase with increasing F-T cycles, reaching a minimum of 0.08, 16.48°, and 3.92 ms in the third cycle, respectively. The swelling rate showed opposite trends with a maximum of 5.92. In addition, scanning electron microscopy observation and mechanical testing confirmed homogeneous pore structure and excellent mechanical properties during the third cycle. This study can provide technical support for fabricating hydrogel absorbent pads and their application in meat products.