壳聚糖-蒙脱土与壳聚糖-高岭土纳米复合涂料流变性及其对纸张阻隔性能的影响

Study of Rheological Property of Chitosan-montmorillonite and Chitosan-clay Nanocomposites and the Effect of Its Application in Coatings on the Barrier Property of Paper

中文关键词:  壳聚糖-蒙脱土纳米复合涂料  壳聚糖-高岭土纳米复合涂料  流变性  阻隔性能

Key Words:chitosan-montmorillonite nanocomposite  chitosan-clay nanocomposite  rheology property  barrier property

中文摘要:

      分析了不同的硅酸盐用量和搅拌速度对壳聚糖-蒙脱土和壳聚糖-高岭土纳米复合涂料流变性的影响；借助原子力显微镜(AFM)观察了涂覆这2种纳米复合涂料后白卡纸的表面形貌,并探讨了这2种涂料对纸张阻隔性能的影响。结果显示,随蒙脱土用量的增加,壳聚糖-蒙脱土纳米复合涂料的黏度增大,但当蒙脱土用量为12%时,涂料黏度下降；蒙脱土的搅拌速度越大,表观黏度对剪切速率的依赖性越大,壳聚糖-蒙脱土纳米复合涂料属于典型的非牛顿假塑性流体,表现出典型的“剪切变稀”现象。随高岭土用量的提高,壳聚糖-高岭土纳米复合涂料的黏度增加,其非牛顿性要大于壳聚糖-蒙脱土纳米复合涂料；随高岭土搅拌速度的提高,壳聚糖-高岭土纳米复合涂料出现了典型的“剪切增黏”现象。相同工艺条件下,壳聚糖-高岭土纳米复合涂料的黏度高于壳聚糖-蒙脱土纳米复合涂料。AFM结果显示,经纳米复合涂料涂布后纸张的粗糙度较原纸显著降低,且壳聚糖-蒙脱土纳米复合涂料对纸张阻隔性能的影响优于壳聚糖-高岭土纳米复合涂料。

Abstract:

      The influence of different dosage of silicate and dispersing rate on the rheolgical properties of chitosan-montmorillonite and chitosan-clay nanocomposites were studied by using the rheological analyzer. The surface morphological characteristics of the papers which were respectively coated with the two nanocomposites were analysed by AFM. Water vapor transmission rate of the coated paper was also investigated. The results showed that the viscosity of chitosan-montmorillonite nanocomposite increased with the content of montmorillonite increasing. But the viscosity of fluid decreased when the dosage of montmorillonite was 12%, because of the intensive wrapping effect of chitosan to montmorillonite and the water swelling of montmorillonite. The greater the dispersion velocity of montmorillonite, the greater the dependence of the apparent viscosity of fluid to the shear rate. Chitosan-montmorillonite nanocomposite was a typical non-newtonian pseudoplastic fluid and showed a typical “shear thinning” phenomenon. The viscosity of chitosan-clay nanocomposite increased with the dosage of clay increasing. Its non-newtonian behavior was more significant than chitosan-montmorillonite. The phenomenon of shear thickening happened with the dispersion velocity increasing, because mechanical stirring force was not enough to destroy the strong hydrogen bonding between the layers of clay. The wrapping effect of chitosan to clay particles was weak. The viscosity of chitosan-clay nanocomposite was higher than that of chitosan-montmorillonite nanocomposite. The better the rheology of fluid, the better formation and smoothness of the coated layers. So the ability to resist water and oxygen vapor permeability of chitosan-montmorillonite nanocomposite was better than that of chitosan-clay nanocomposite．