| Gypsum whiskers is a new kind of high performance inorganic materials, which can effectively improve the paper performance when applied in papermaking industry.However, there are some problems using gypsum whiskers in papermaking process, such as low retention rate and high solubility in pulp solution. So it is not very good to meet the requirements of the papermaking process. Surface modification of gypsum whiskers is used to decrease the solubility in pulp solution and enhance the affinity between whiskers and pulp fiber, increasing the retention rate of gypsum whiskers.In this paper, two methods are used to modify gypsum whiskers. BaSO4-CO2secondary sedimentation method and chitosan were used to the surface chemical coating of gypsum whiskers.The optimal modifying conditions were optimized by single-factor experimental analysis. The effect of modification was discussed separately through the mass fraction of reagents, processing time and processing pH. The structures and properties of modified gypsum whiskers were characterized by SEM, TEM, EDS, XRD, TG-DSC, XPS and FTIR. The coating mechanism was studied too, and the adsorption models between whiskers and modifying agent were also established.The results of the modified samples for the test have shown that the solubility of gypsum whiskers modified with two methods is all decreased. The solubility of gypsum whiskers modified with BaSO4-CO2secondary sedimentation method come down most, the solubility decreases by70%under the optimum condition. The modified gypsum whiskers was applied to papermaking process, preparing paper and testing the properties of paper. The results of the paper properties for the test have shown that the effect of chitosan coating gypsum whiskers is the best, the paper have fairly good performances. The research results have an important guiding significance to the industrialized production of gypsum whiskers modified technology... |
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