MOISTURE MASKS AND CHITOSANS 11 is larger than that of methyl cellulose or that chitosan and its derivatives have excellent water-holding capacities (9,28-31). The results in Figure 3 also show the water-holding capacity of moisture masks increasing with the use of water-soluble chitosans of higher molecular weight. FILM-FORMATION TIME OF MOISTURE MASKS The results in Table VI show film-formation times of moisture masks decreasing with the increasing concentration of water-soluble chitosans used (of the same molecular weight of water-soluble chitosan) or decreasing with the increasing molecular weight of water-soluble chitosans used (of the same concentration of water-soluble chitosan). This may be because film formation results from aggregation of film-forming compounds, i.e., the water-soluble chitosan, after the solvent evaporates (8). Therefore, film- formation time decreased with increasing concentration of film-forming agents and/or decreased with increases in their molecular weights. The reason that moisture masks containing 0.5 g U3 chitosan have film-formation times similar to those of masks containing 2.0 g of methyl cellulose may be due to the fact that the molecular weight of U3 chitosan is larger than that of methyl cellulose, as mentioned previously. CONCLUSIONS 1. Moisture masks containing different molecular weights and/or concentrations of water-soluble chitosans are pseudoplastic fluids. 2. The apparent viscosity of moisture masks increased with the increasing molecular weight and/or concentration of water-soluble chitosans used in the formula. This will improve the stability of the moisture mask, enhance skin hydration, shorten film- formation time, and improve skin compatibility. Thus moisture masks containing water-soluble chitosans will be useful in a wide range of applications. 3. These beneficial effects may be attributed to the good water-holding capacity, thick- ening, and film-formation properties of water-soluble chitosans. ACKNOWLEDGMENTS The authors would like to express their gratitude to the National Science Council, Republic of China (Project No. NSC 86-2313-B-019-006) for its financial support. REFERENCES (1) A. Domard, G. A. F. Roberts, and K. M. Varum, Eds., Advances in Chitin Science, Volume II. (Jacques Andre, Lyon, France, 1997). (2) R. H. Chen and H. C. Chen, Eds., Advances in Chitin Science, Volume III (RITA Advertising Co., Ltd., Taipei, Taiwan, ROC, 1999). (3) C. Y. Chang, The effect of adding chitinous materials on the qualities of the Alaska pollack kamaboko. MS Thesis, National Taiwan Ocean University (in Chinese), 1997. (4) G. Lang, E. Konran, and H. Wendel, "Chitosan Derivatives: Water-Soluble Products by Reaction with Epoxides," in Chitin in Nature and Technology, R. Muzzarelli, C. Jeuniaux, and G. W. Gooday, Eds. (Plenum Press, New York, 1986), pp. 303-306.

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