ABSTRACT

Unidirectional freeze casting for polymers and ceramics has been performed extensively; however, the mechanisms involved in unidirectional freezing are not thoroughly understood and therefore, in this study, polyvinyl (alcohol) hydrogels were freeze-thawed by unidirectional freezing and the resultant freezing profile was investigated using thermal imagery to comprehend the physical mechanism involved in the production of these aligned cryogels. The approach used follows a slight variation from what is currently used in literature, by enclosing the mould with insulating materials and leaving one side with a metal encasing for a fast freezing flow from the direction of the desired aligned of the structure. This method was cost-effective and simple; however, it was able to induce unidirectional freezing resulting in two distinct structures. These structures exhibited a cellular region interspersed with a fibrous and porous morphology. The method developed without the need of a freeze-dryer was confirmed to produce a unidirectional freezing which can be used for future studies.

摘要

已经广泛地进行了用于聚合物和陶瓷的单向冷冻浇铸。但是，单向冻结的机理尚不完全清楚，因此，在这项研究中，聚乙烯醇（水凝胶）通过单向冻结进行了解冻，并使用热成像法研究了所得的冻结曲线，以了解生产中涉及的物理机理。这些对齐的冰晶。所采用的方法与目前文献中所使用的方法略有不同，方法是用绝缘材料将模具封闭，并在一侧留有金属外壳，以便从所需结构对准方向快速冷冻流动。这种方法既经济又简单。但是，它能够诱导单向冻结，从而产生两个不同的结构。这些结构表现出散布有纤维和多孔形态的细胞区域。经证实，无需冷冻干燥机而开发的方法可产生单向冷冻，可用于将来的研究。