Silk fibers morphology

Grubb, D.T., and Jelinski, L.W. "Fiber morphology of spider silk the effects of tensile deformation". Macromolecules 30(10), 2860-2867 (1997). 

Miller, L.D., Putthanarat, S., Eby, R.K., and Adams, W.W. "Investigation of the nanofibrillar morphology in silk fibers by small angle X-ray scattering and atomic force microscopy". Int. ]. Biol Macromol. 24(2-3), 159-165 (1999). 

Zarkoob, S., Reneker, D.H., Eby, R.K., Hudson, S.D., Ertley, D., and Adams, W.W. Structure and morphology of nano electrospun silk fibers. Abstracts of Papers of the American Chemical Society (1998), 216, U122-U122. 

The fractured surfaces of the broken silk fibers were classified according to Hearle s system of fiber fracture morphology (8). Most fractured... 

Figure 8. Surface morphology of silk fibers (500X).

The fracture surfaces of the tensile test specimens were examined by SEM. To study the surface morphology of the prepared composites, SEM photographs were taken for 30, 35, 40, and 45% fiber volume fraction, as shown in Figure 15. The SEM of fracture surface of composite indicates that fiber pullout occurs. This is due to lack of interfacial adhesion between silk and PP matrix. Due to intermolecular hydrogen bond formation between silk fibers and hydrophobic nature of PP matrix, hydrophilic silk fibers tend to agglomerate into bundles (Figure 15(d)), and become unevenly distributed throughout the matrix. It is seen that for 40% fiber volume fraction composite, less fiber pullout happens, better interfacial adhesion between silk and PP matrix occurs. 

In an attempt to document the effect of the deep ocean environment on textile materials, modem materials were immersed at the site on the ocean floor for subsequent retrieval. While one set of samples was recovered after a three month period, additional samples have remained on the ocean floor since 1991 and are yet to be retrieved. The morphology of cellulosic fibers immersed for a three-month period has been investigated (S), The physical and chemical structure of dyed and undyed cotton fibers from the site compared with those of modem cotton and of cotton immersed on the ocean floor for three months were reported (70,77). Results of preliminary analyses on silk fibers using differential scanning calorimetry, energy dispersive x-ray spectoscopy, and scanning electron microscopy, have been reported (72). 

In comparison to Reference Silk and Historic Silk fibers, the Marine Silk fibers show more extensive morphological damage with deep cracks, surface striations, fibrillation, and fiber flattening. These changes in morphology, combined with the increased diameter of two of the Marine Silks, reflect changes in the physical microstructure of the artifacts as a result of the deep ocean environment. 

Silk. Silk, like wool, is a protein fiber, but of much simpler chemical and morphological makeup. It is comprised of six alpha amino acids, and is the only continuous-filament natural fiber. Historians claim that silk was discovered in China in 2640 b.c. Silk fiber is spun by the silkworm as a double strand, each part having a trilobal cross section. This configuration helps give silk its lustrous appearance. The fiber is wound from the cocoon that the silkworm spins as it prepares its chrysalis. The filaments are smooth and have no twist in their length, which can vary from 300 to 1800 yards. The diameter of silk is very fine, ranging from 2 to 5 microns. Because of the labor-intensiveness of silkworm culture and subsequent preparation of the fiber, silk remains a luxury fiber with a limited market niche. 

Fiber morphology and diameter distribution of electrospun spider silk. 

Morphology of cells on natural silkworm silk fibers and nanofibers after 7 days in culture. 

Notice that silk fibroin dissolved from Bombyx mori silk fibers can be reformulated into silk fibroin films by casting solutions of silk proteins onto a substrate and allowing the evaporation of the solvent. As-cast films made from aqueous solutions of silk fibroin are mechanically weak and typically unstractured or a-heUx-rich [5, 42]. In tissue engineering studies, in order to modulate the mechanical properties and the rate/extent of degradation, the crystalline state (/3-sheet content) and morphology need to be controlled [8]. 

Recently, Foo et al. (2006) produced some novel nanocomposites from spider silk-silica fusion (chimeric) proteins. The composite morphology and structure could be regulated by controlling processing conditions to produce films and fibers. Silk and biomineralization being natural inspiration sources will allow production of numerous new materials in various fields of application. 

External hair of animals, generally called wool, was spun into yam and woven into fabrics. Like silk, wool is essentially protein it is composed of various amino acids, a majority of which are keratin. (Unfortunately, the keratin contains sulfur, which attracts certain insects that thrive on wool and contribute to the scarcity of historic woolen fabrics.) The outstanding morphological characteristic of wool fiber is its external scales that overlap in one direction toward the tip of the fiber. The scales can be chemically, mechanically, and temporally damaged and can disappear as the wool deteriorates. Outside of the scales is a membranous layer, the epicuticle inside them is the bulk of the wool fiber, the cortex, which consists of millions of double-pointed, needle-like cells neatly laid... 

Silk concentration plays a major role in fiber diameter. No fibers were formed at less than 5% silk concentration for any electric field and spinning distances. Figures. 22 and 23 show the morphology of fibers obtained at the electric fields of 3 and 4 kV/cm, respectively, at silk/formic acid concentrations of 5, 8, 10, 12, 15, and 19.5% with a constant tip-to-collection plate distance of 7 cm. 

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