Nordqvist David, Idermark Johan, Hedenqvist Mikael S, Gällstedt Mikael, Ankerfors Mikael, Lindström Tom
School of Chemical Science and Engineering, Fibre and Polymer Technology, Royal Institute of Technology, SE-100 44 Stockholm, Sweden.
Biomacromolecules. 2007 Aug;8(8):2398-403. doi: 10.1021/bm070246x. Epub 2007 Jul 24.
This report presents a new route to enhance the wet properties of chitosan-acetic-acid-salt films using microfibrillated cellulose (MFC). The enhancement makes it easier to form chitosan-acetic-acid-salt films into various shapes at room temperature in the wet state. Chitosan with MFC was compared with the well-known buffer treatment. It was observed that films containing 5 wt % MFC were visually identical to the buffered/unbuffered films without MFC. Field-emission scanning electron microscopy indicated that MFC formed a network with uniformly distributed fibrils and fibril bundles in the chitosan matrix. The addition of MFC reduced the risk of creases and deformation in the wet state because of a greater wet stiffness. The wet films containing MFC were also extensible. Although the stiffness, strength and extensibility were highest for the buffered films, the wet strength of the MFC-containing unbuffered films was sufficient for wet forming operations. The effects of MFC on the mechanical properties of the dry chitosan films were small or absent. It was concluded that the addition of MFC is an acceptable alternative to buffering for shaping chitosan films/products in the wet state. The advantages are that the "extra" processing step associated with buffering is unnecessary and that the film matrix remains more water-soluble.
本报告介绍了一种利用微纤化纤维素（MFC）增强壳聚糖 - 醋酸盐薄膜湿态性能的新途径。这种增强使得在室温下湿态时更容易将壳聚糖 - 醋酸盐薄膜加工成各种形状。将含MFC的壳聚糖与著名的缓冲处理进行了比较。观察到含5 wt% MFC的薄膜在外观上与不含MFC的缓冲/未缓冲薄膜相同。场发射扫描电子显微镜表明，MFC在壳聚糖基质中形成了具有均匀分布的原纤维和原纤维束的网络。由于具有更高的湿态刚度，添加MFC降低了湿态时起皱和变形的风险。含MFC的湿膜也具有可拉伸性。尽管缓冲薄膜的刚度、强度和可拉伸性最高，但含MFC的未缓冲薄膜的湿强度足以满足湿成型操作。MFC对干壳聚糖薄膜力学性能的影响很小或不存在。得出的结论是，添加MFC是在湿态下对壳聚糖薄膜/产品进行成型时缓冲处理的一种可接受的替代方法。优点是不需要与缓冲相关的“额外”加工步骤，并且薄膜基质保持更高的水溶性。
