Abstract: A series of chitosan of different viscosity-average molecular weight were prepared by oxidation of chitosan with hydrogen peroxide as the oxidizing agent.The chitosan of different viscosity-average molecular weight was applied as paper surface sizing agent,and the effect to the surface properties of the paper was studied.Results showed that the reducing of chitosan viscosity-average molecular weight is not beneficial to its surface sizing effect.Such result was confirmed by SEM.Under same conditions,as comparing with using oxidized starch alone,the mixture with a small amount of chitosan and oxidized starch can improves the surface strength of paper obviously.

Key words: chitosan, degradation, surface sizing, oxidized starch