不同干燥方式对细菌纤维素物理性能的影响

Effects of Different Drying Processes on Physical Properties of Bacterial Cellulose Membranes

摘要:

本文考察不同干燥方式对细菌纤维素的物理性能的影响。采取3种不同干燥的方法分别对细菌纤维素膜进行干燥，分别为：60 ℃烘箱中干燥（BC-DHT）；在-20 ℃冷冻结实后冷冻干燥（BC-FDF）；在液氮中迅速冷冻结实，然后冷冻干燥（BC-FDN）。通过扫描电子显微镜观察，BC-FDN的内部结构比BC-FDF和BC-DHT更松散。在吸水性能方面，BC-DHT、BC-FDF、BC-FDN每克纤维素吸水量分别为2.38 g、6.22 g、58.24 g。在透湿率方面，BC-FDN的透湿性能最好，其次为BC-FDF，而BC-DHT透湿性能最差。对BC-DHT、BC-FDF、BC-FDN进行X射线衍射分析，从其衍射图谱分析所得结晶指数分别为78.5%、64.2%、47.5%。热重分析结果分析所得，BC-DHT的热稳定性较好，其次为BC-FDF，而BC-FDN的热稳定性最差。由此可见，通过不同的干燥方法能改变细菌纤维素的物理性质。

Abstract:

The physical properties of bacterial cellulose (BC) prepared using different drying methods were investigated. Three different drying methods for bacterial cellulose membrane included (1) drying at elevated temperature (60 ℃) (BC-DHT), (2) frozening at -20 ℃, and then freeze-drying (BC-FDF), and (3) shock frozening with liquid nitrogen and subsequently freeze-drying (BC-FDN). The scanning electron microscope (SEM) showed that BC-FDN had larger pores and empty spaces than BC-DHT and BC-FDF. One gram of dry BC samples could absorb 2.38 g, 6.22 g, and 58.24 g water for BC-DHT, BC-FDF, and BC-FDN, respectively. The water vapour transmission rate were in the order of BC-FDN?BC-FDF?BC-DHT. X-ray diffraction (XRD) indicated that the crystallinity indexes of BC samples were 78.5%, 64.2%, and 47.5% for BC-DHT, BC-FDF, and BC-FDN, respectively. Thermogravimetric analysis showed that the thermal stability of BC-DHT was better than those of BC-FDF and BC-FDN. Thus, the physical properties of bacterial cellulose can be altered by different drying methods.