Mechanical, Thermal, and Swelling Properties of Cross-linked Hydrogels Based on Oxidized Cellulose Nanowhiskers and Chitosan/poly(vinyl alcohol) Blends

Cross-linked hydrogels of chitosan/poly(vinyl alcohol) (PVA)/oxidized cellulose nanowhiskers (CNWs) were prepared by using oxidized CNWs as a cross-linker. The effects of the oxidation level of CNWs on the swelling behavior, thermal stability, viscoelastic properties and compressive strength of the hydrogels were studied. Chemical cross-links, hydrogen bonds, as well as nanofiller reinforcement between the three materials played a major role in determining the properties of the hydrogels. Swelling test results showed that the incorporation of oxidized CNWs decreased the water absorbability of the hydrogels due to the increase in cross-linking degree. Viscoelastic properties of the hydrogels with oxidized CNWs was increased by 537 % in storage modulus, from 4.65 kPa to 29.6 kPa. Compressive strength of 181.5 kPa at 50 % strain was observed from the cross-linked hydrogels, compared with 21.2 kPa of the non-cross-linked hydrogels. The thermal experiments showed that the chemical cross-linking slightly increase the resistance toward thermal degradation of the hydrogels.