壳聚糖改性石膏晶须及在造纸中的应用研究

The Application of Chitosan Modified Gypsum Whisker in Papermaking

采用壳聚糖对石膏晶须进行改性,降低石膏晶须的溶解度,提高其作为填料在纸浆纤维中的留着率。研究了壳聚糖的用量、p H值等因素对其溶解度的影响,采用扫描电子显微镜(SEM)、X射线衍射仪(XRD)、X射线光电子能谱仪(XPS)等方法对改性后的石膏晶须进行表征,并对改性的机理进行了研究。结果表明,当壳聚糖用量为0.5%,溶胶p H值为5.5,凝胶p H值为7.5时,改性后石膏晶须的溶解度最小,为5.6%,与未改性的石膏晶须相比下降了60%。SEM、XRD及XPS分析结果表明,壳聚糖有效包覆在石膏晶须的表面,且壳聚糖的包覆厚度为9.8 nm。将改性石膏晶须作为填料抄造手抄片,并对纸张相关性能进行检测,结果表明,与未改性石膏晶须加填纸相比,加入改性石膏晶须纸样的Cobb值提高了15.3%,填料留着率提高了15.1%,抗张指数提高了5.6%。

To improve the performance of gypsum whiskers in papermaking, chitosan coated gypsum whiskers aiming to reduce its solubility in aqueous solution effectively were prepared. The influences of the content of chitosan, reaction pH were explored. The chitosan-gypsum whiskers were characterized by SEM, XRD, XPS. The mechanism of the modification was studied. The results showed that the best modification conditions were ： 0. 5% chitosan, sol pH 5.5, gel pH 7.5, the solubility of chitosan-gypsum whiskers reduced from 14. 0% to 5.6% under the conditions. SEM, XRD and XPS results showed that, chitosan covered the furface of gypsum whiskers effectively, and the cover thickness of ehitosan is 9.8 nm. Cobber number, filler retention and tensile strength of handsheet with modified gypsum whiskers increased by 15.3%, 15.1% and 5.6% compared to that of unmodified gypsum whisker.