Preparation and properties of PVA/PVP hydrogels containing chitosan by radiation

Radiation can induce chemical reactions to modify polymers even when they are in the solid state or at a low temperature. Radiation crosslinking can be easily adjusted by controlling the radiation dose and is reproducible. The finished product contains no residuals of substances required to initiate the chemical crosslinking, which can restrict its application possibilities. In these studies, hydrogels for wound dressing were made from a mixture of chitosan and polyvinyl alcohol (PVA)/poly-N-vinylpyrrolidone (PVP) by freezing and thawing, gamma-ray irradiation, or combined freezing and thawing and gamma-ray irradiation. The physical properties of the hydrogel, such as gelation, water absorptivity, and gel strength, were examined to evaluate the usefulness of the hydrogels for wound dressing. The PVA/PVP composition was 60:40, PVA/PVP-chitosan ratio was in the range 9:1-7:3, and the concentration of, PVA/PVP-chitosan as a solid was 15 wt %. A mixture of PVA/PVP-chitosan was exposed to gamma irradiation doses of 25, 35, 50, 60 and 70 kGy to evaluate the effect of irradiation dose on the physical properties of hydrogels. Water-soluble chitosan was used in these experiment. The physical properties of the hydrogels, such as gelation and gel strength, were higher when the combination of freezing and thawing and irradiation were used rather than just freezing and thawing. The PVA/PVP-chitosan composition and irradiation dose had a greater influence on swelling than gel content, Swelling percent increased as the composition of chitosan in PVA/PVP-chitosan increased. (C) 2002 Wiley Periodicals, Inc.