The Structure and Properties of Ultrathin Films Blended from Nanofibrils of Natural Fibers.

本研究以天然纳米纤维为原料，制备了一种新型的可生物降解超薄膜，并对其表面结构和力学性能进行了分析。以木浆(漂白硫酸盐浆、纤维素)、壳聚糖(商品级)和胶原蛋白(牛皮下脚料)三种天然纤维为原料。一台带有专门设计的圆盘的小型商用研磨机被用来对天然纤维进行纳米原纤化。所有材料都被控制为含90-99%水的浆料。从木浆中得到的纤维直径约为几纳米，从壳聚糖和胶原蛋白中得到的纤维直径在十几纳米左右。以水悬浮液为原料制备了一种新型的超薄膜。这些薄膜的厚度从大约几百纳米到大约几十纳米不等，均匀、坚固和半透明。采用这种不使用有机溶剂的水悬浮法，可以很容易地制备出三种非晶玻璃的超薄膜。通过结构分析，超薄膜中的每个非晶玻璃都平行于其表面。通过微纤化的方法制备了其超薄膜的形成过程，并与溶剂浇铸法制备的普通薄膜进行了比较。现在，我们能够制备具有多种用途的薄膜杂化薄膜。木浆、壳聚糖和胶原的混合物制成的薄膜是印刷级纸的1.5倍左右，是聚乙烯的2倍左右。这些膜的价值足以用于实际应用。

In this study, a new type of the biodegradable ultrathin films have been developed using natural nanofibrils (NFs), and the surface-structure of their ultrathin films and mechanical properties are analyzed. Three kinds of natural fibers, wood pulp (bleached kraft pulp, cellulose), chitosan (commercial grade) and collagen (cow hide waste) were used as raw materials. A small commercial grinder with a specially designed disk was used to nanofibrillate the natural fibers. All the materials were controlled as a slurry containing 90 - 99 % water. The diameter of their NFs from wood pulp was about some nanometer and the diameter of the some ones from chitosan and collagen were some ten nanometer. A new type of ultrathin film was made from the water suspension of NFs. The thicknesses of these films were from about some hundreds nanometer to about some tens nanometer, being homogeneous, strong and translucent. The ultra thin films of three kinds of NFs were easily obtained by this water-suspension method without using an organic solvent. Each NFs in ultrathin films is oriented to parallel to its surface plane by structural analysis. The formation process of their ultrathin films was made by microfibrillating the NFs, and then their networks of microfibril were compared with the ordinary films of solvent-cast method. Now, we are able to prepare thin hybrid films which are expected for many uses. The thin film from the mixture of wood pulp, chitosan and collagen was about 1.5 times of that of print grade paper and about 2 times of that of polyethylene. These values of the films are sufficient for practical use.