CHANGES IN THE INTERNAL FINE STRUCTURE OF SILK FIBROIN BY DRAWING
CHANGES IN THE INTERNAL FINE STRUCTURE OF SILK FIBROIN BY DRAWING
复制标题
丝素内部精细结构的拉伸变化
DOI：
10.2115/fiber.25.440
复制
发表时间：
1969
期刊：
影响因子：
--
通讯作者：
M. Kakudo
中科院分区：
文献类型：
--
作者：
K. Hirabayashi;H. Ishikawa;M. Kakudo
利用X射线衍射、偏光显微镜和电子显微镜等手段，研究了拉伸对柞蚕丝素α-β转变和空洞形成的影响。其中多肽中的疏水残基排列在内部，亲水残基排列在外部。这种结构被凝胶的拉伸破坏。随着拉伸倍数的增加，分子的α-螺旋结构逐渐转变为伸展的β-结构，当拉伸倍数大于6- 8倍时，β-结构占主导地位。然而，即使在最高拉伸比14下，仍保留少量的α α-构象。试样的堆积度（初始堆积度为36%）先减小后增大，在拉伸比为8时达到最小值。另一方面，双折射率随拉伸比的增加而缓慢但单调地增加。2）通过显微镜和小角X射线方法研究了孔洞的形成机制以及拉伸对其形状的影响。据认为，空隙的形成是由已经被封闭在凝胶中的水的排放引起的。通过拉伸凝胶，这种空隙变得更小和更长，并且在纤维轴的方向上对齐，空隙的长度与宽度的比率达到2。
Effects of drawing on the α-β transition and the formation of voids in Tussah silk fibroin were studied by means of X-ray diffraction at wide and small angles, polarizing microscopy, and electron microscopy.1) It is found that the fibroin coagulated in silk gland has a morphology of small spherulitic particles (ca. 240A in radius) in which hydrophobic residues in the polypeptide are arranged in the inner part and the hydrophilic residues in the outer part. This structure is destroyed by the drawing of gel. The α-helix form of the molecule changes gradually into the extended β-form as the draw ratio increases: the β-component becomes predominant at the draw ratio higher than 6-8times. However a small amount of αa-conformation still remains even at the highest draw ration 14. The crystallinityof the specimen (36% at the beginning) decreases at first but turns to increase, having a minimum at the draw ratio of 8. On the other hand, the birefringence increases slowly but monotonously as the draw ratio.2) The mechanism of the void formation as well as the effects of drawing on their shapes was examined through use of microscopies and a small-angle X-ray method. It is considered that the formation of voids is caused by the emission of water which have been occluded in the gel. Such voids become smaller and longer by drawing the gel and align in the direction of the fiber axis, the ratio of the length to the width of the voids attaining two.