纳米镁化合物对壳聚糖复合涂膜性能的影响

Influence of Nanometer Magnesium Compound on the Performances of the Composited Chitosan Coatings

以纳米镁化合物改性壳聚糖涂膜,不仅能改善涂膜的力学性能和透气性能,还可增强其抗菌性能。以纳米镁化合物作为壳聚糖改性材料的涂膜研究,国内外鲜见报道。为探讨镁化合物纳米粉体对壳聚糖涂膜性能的影响,测定了不同形貌纳米镁化合物粉体添加改性后壳聚糖涂膜的性能指标,并对这种壳聚糖涂膜进行SEM、XRD及FT-IR表征。结果表明,镁化合物纳米粉体表面的活性基团与壳聚糖作用,导致壳聚糖的FormⅠ晶型减少,FormⅡ晶型发生改变。添加Mg_2(OH)_3Cl纳米片和纳米MgO颗粒后,壳聚糖复合涂膜的力学性能增强,透湿性能减弱;然而由于MgO纳米棒和MgO纳米小球在涂膜中存在团聚现象,所以导致壳聚糖与纳米粉体不能很好结合,涂膜内产生空隙甚至裂缝,涂膜机械性能下降及透湿性能增强。添加纳米MgO颗粒对壳聚糖涂膜的透O_2性、透CO_2性改良效果最佳。镁化合物纳米粉体对壳聚糖涂膜的光学性能影响不显著,说明添加镁化合物纳米粉体不影响涂膜在食品保鲜中的应用。

In order to investigate the influence of nanometer magnesium compounds on the performances of the composited chitosan coatings, the chitosan coating performance indicators were measured which were modified by magnesium compounds nano-powders with different morphologies, and the samples were characterized by SEM, XRD and FT-IR.The results show that polymorph Form Ⅰof chitosan is decreased, polymorph of Form Ⅱis changed due to the reaction of the active group on the surface of magnesium compounds and chitosan. After modified by Mg2（OH）3Cl nanosheets or nano-MgO particles, the mechanical properties of chitosan coating is enhanced and the moisture permeability is decreased. When the chitosan coatings are modified by MgO nanorods and nano-MgO pellets, a part of particles are aggregated in the chitosan coating. The powders are not combined with chitosan well, and the pores or cracks are presented in the coating, so the mechanical properties are decreased and water vapor permeabilities are enhanced. Modified by MgO nano-particles, the chitosan coatings get the optimal O2, CO2 permeabilities. The optical properties of the chitosan coating are not affected by nano magnesium compounds. It means that the chitosan coating modified by nano magnesium compounds can be applied in food preservation.