纤维素/壳聚糖共混透明膜的制备及阻隔抗菌性能研究

Preparation and Properties of Cellulose/Chitosan Transparent Films

利用壳聚糖溶液包覆法制备了具有高气体阻隔性及抗菌性的透明纤维素膜,其扫描电镜照片证明壳聚糖厚度在1.31~4.07μm之间.通过红外光谱、紫外光谱、热重分析仪、电子万能试验机和接触角测试仪对纤维素/壳聚糖共混膜的结构和性能进行了详细研究,结果表明由于壳聚糖和纤维素之间具有一定的氢键相互作用,使得纤维素/壳聚糖共混膜较好地保持了纯纤维素膜的机械强度,其拉伸强度都大于110 MPa.此外,壳聚糖的包覆对纤维素膜的透明性没有影响,它在600~800 nm处的透光率仍维持在80%左右,并且提高了纤维素膜的疏水性,其水接触角从纤维素膜的70°提高到了100°.利用气体渗透仪进一步研究了纤维素/壳聚糖共混膜的氧气阻隔性,结果表明该膜具有很好的氧气阻隔性,其氧气渗透系数甚至低于市场上理想的氧气阻隔材料乙烯-乙烯醇共聚物（EVA）.金黄色葡萄球菌抗菌测试表明,通过壳聚糖包覆法改性纤维素能够明显提高纤维素膜的抗菌性.

Cellulose films with antimicrobial activity and high gas barrier properties are successfully prepared by a facile surface coating chitosan approach. The cellulose wet film was prepared from an ionic liquid （IL） , 1- allyl-3-methylimidazolium chloride （AmimC1） by coagulating in water. After that, the cellulose film was immersed in the chitosan-acetic acid solution with different concentrations for 2 h,and then dried in air for 24 h. Via this method, most chitosan was distributed in the surface of cellulose film, which was demonstrated by SEM-EDX,and the film had good hydrophobicity and antimicrobial activity. Scanning electron microscope images indicate that the thickness of chitosan layer on the cellulose films is in the range of 1.31 μm to 4.07 μm,which can be controlled by the concentration of chitosan. FTIR and TG results demonstrate that there is hydrogen bond interaction between cellulose and chitosan. Besides this, SEM images displayed a homogenous and smooth morphology, indicating a good compatibility between cellulose and chitosan. The optical transmittance of the blend films was maintained well compared with the cellulose film reaching 80% transmittance at 600 -800 nm owing to the low thickness of chitosan layer. Due to the interaction between chitosan and cellulose,the blend films have good mechanical properties,their tensile strengths are greater than 110 MPa. Their oxygen permeability results showed that the blend films had high gas barrier capacity, exceeding the ideal commercial oxygen barrier material ethylene-vinyl acetate eopolymer （EVA）. The cellulose/chitosan blend films showed effective antimicrobial capability against Staphylococcus aureus examined by the antimicrobial test. The obtained results indicate that the cellulose/chitosan blend films may be suitable for use in the food packaging fields.