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

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。

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 fxeeze-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-FDE 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.