Gindl Wolfgang, Martinschitz Klaus J, Boesecke Peter, Keckes Jozef
Department of Materials Science and Process Engineering, University of Natural Resources and Applied Life Sciences, Vienna, Austria.
Biomacromolecules. 2006 Nov;7(11):3146-50. doi: 10.1021/bm060698u.
Cellulose films were prepared by dissolving lyocell fibers in LiCl/N,N-dimethylacetamide solvent and subsequently coagulating and drying them under ambient conditions. To introduce preferred orientation, the films were uniaxially drawn under air-dry and rewetted conditions, respectively. Preferred orientation was determined by birefringence measurements and by wide-angle X-ray scattering. Mechanical properties were characterized by means of tensile tests with films conditioned to standard temperatures and humidity. Drawing resulted in the substantial reorientation of cellulose, whereby the molecular chains in the amorphous regions exhibited clearly stronger reorientation than the crystalline fraction. The average degree of orientation was comparable to orientation achieved in spun cellulose fibers. Wet-drawing resulted in improved tensile strength and modulus of elasticity but reduced elongation at break. The mechanical properties of wet-drawn films are competitive with regard to cellophane and melt-blown cellulose films, particularly considering their high modulus of elasticity of up to 26 GPa, which is also comparable to values obtained for industrially produced cellulose fibers.
通过将莱赛尔纤维溶解在LiCl/N，N-二甲基乙酰胺溶剂中，随后在环境条件下进行凝固和干燥来制备纤维素薄膜。为了引入择优取向，分别在风干和再湿润条件下对薄膜进行单轴拉伸。通过双折射测量和广角X射线散射来确定择优取向。通过对薄膜在标准温度和湿度条件下进行拉伸试验来表征其机械性能。拉伸导致纤维素发生大量的重新取向，由此非晶区的分子链表现出比结晶部分明显更强的重新取向。平均取向度与纺制纤维素纤维中实现的取向度相当。湿拉伸导致拉伸强度和弹性模量提高，但断裂伸长率降低。湿拉伸薄膜的机械性能与玻璃纸和熔喷纤维素薄膜相比具有竞争力，特别是考虑到它们高达26 GPa的高弹性模量，这也与工业生产的纤维素纤维所获得的值相当。
