Silk fiber

Microdenier nylon and polyester were a significant spinning breakthrough when demonstrated in 1985. The finer-than-silk fibers added a new dimension to fabric aesthetics, comfort, and performance. Microdenier nylons are used in weaving, warp knits, and weft knits for sports-, leisure-, and... 

Resistance to axial compressive deformation is another interesting property of the silk fibers. Based on microscopic evaluations of knotted single fibers, no evidence of kink-band failure on the compressive side of a knot curve has been observed (33,35). Synthetic high performance fibers fail by this mode even at relatively low strain levels. This is a principal limitation of synthetic fibers in some stmctural appHcations. 

Thermal Properties. Spider dragline silk was thermally stable to about 230°C based on thermal gravimetric analysis (tga) (33). Two thermal transitions were observed by dynamic mechanical analysis (dma), one at —75° C, presumed to represent localized mobiUty in the noncrystalline regions of the silk fiber, and the other at 210°C, indicative of a partial melt or a glass transition. Data from thermal studies on B. mori silkworm cocoon silk indicate a glass-transition temperature, T, of 175°C and stability to around 250°C (37). The T for wild silkworm cocoon silks were slightly higher, from 160 to 210°C. 

Silk fibers, which have incredible strength, comprise well-ordered microcrystals of P-sheets that make up about 30% of the protein mass, interspersed in a matrix of polypeptide chains without order. The p strands of the sheets are oriented parallel to the fiber axis. 

Bram, A., et al. X-ray diffraction from single spider silk fibers. J. Appl. Cryst. 30 390-394, 1997. 

Fibers obtained from living organisms are known as animal fibers, e.g., wool, which is obtained from domestic sheep silk fiber, which is produced by the silkworm... 

Lazaris, A., Arcidiacono, S., Huang, Y., Zhou, J.F., Duguay, F., Chretien, N., Welsh, E.A., Soares, J.W., and Karatzas, C.N., Spider silk fibers spun from soluble recombinant silk produced in mammalian cells. Science, 295(5554), 472- 76, 2002. 

Short fiber reinforcement of TPEs has recently opened up a new era in the field of polymer technology. Vajrasthira et al. [22] studied the fiber-matrix interactions in short aramid fiber-reinforced thermoplastic polyurethane (TPU) composites. Campbell and Goettler [23] reported the reinforcement of TPE matrix by Santoweb fibers, whereas Akhtar et al. [24] reported the reinforcement of a TPE matrix by short silk fiber. The reinforcement of thermoplastic co-polyester and TPU by short aramid fiber was reported by Watson and Prances [25]. Roy and coworkers [26-28] studied the rheological, hysteresis, mechanical, and dynamic mechanical behavior of short carbon fiber-filled styrene-isoprene-styrene (SIS) block copolymers and TPEs derived from NR and high-density polyethylene (HOPE) blends. 

The feeling of a spider web may be unsettling, but a similar natural material has been used for centuries to make silk fabric that is prized for its smooth texture. Silkworms produce the silk fibers used to make clothing. They feast on mulberry leaves and convert the molecules from these leaves into silk, from which they spin cocoons. 

Silky - when it reflects light in a silk-fiber manner... 

Silk fibers, a basic system with a uniaxial symmetry, have also been investigated by Raman spectromicroscopy [63] that is one of the rare techniques capable of providing molecular data on such small (3-10 pm diameter) single filaments. The amide I band of the silk proteins has been particularly studied to determine the molecular orientation using the cylindrical Raman tensor approximation. In this work, it was assumed that Co Ci, C2 and the a parameter was determined from an isotropic sample using the following expression of the depolarization ratio... 

Finally, as in macro-Raman experiments, orientation-insensitive spectra can also be calculated for spectromicroscopy. A method has been developed recently for uniaxially oriented systems and successfully tested on high-density PE rods stretched to a draw ratio of 13 and on Bombyx mori cocoon silk fibers [65]. This method has been theoretically expanded to biaxial samples using the K2 Raman invariant and has proved to be useful to determine the molecular conformation in various polymer thin films [58]. 

Takeuchi et at. [60] reported that cloth made of raw silk (R-silk) fiber forms hydroxyapatite in 1.5SBF but cloth made of normal silk (N-silk) fiber does not. The surfaces of raw silk and normal silk fibers consist of sericin and fibroin, respectively. 

Takeuchi, A., Ohtsuki, C., Miyazaki, T., Tanaka, H., Yamazaki, M. and Tanihara, M. (2003) Deposition of bone-like apatite on silk fiber in a solution that mimics extracellular fluid. Journal of Biomedical Materials Research, 65A, 283-289. 

Synthetic Spider Silk Fibers Natural i/s Artificial Spinning Strategies... 

Silk fibers or monolayers of silk proteins have a number of potential biomedical applications. Biocompatibility tests have been carried out with scaffolds of fibers or solubilized silk proteins from the silkworm Bombyx mori (for review see Ref. [38]). Some biocompatibility problems have been reported, but this was probably due to contamination with residual sericin. More recent studies with well-defined silkworm silk fibers and films suggest that the core fibroin fibers show in vivo and in vivo biocompatibility that is comparable to other biomaterials, such as polyactic acid and collagen. Altmann et al. [39] showed that a silk-fiber matrix obtained from properly processed natural silkworm fibers is a suitable material for the attachment, expansion and differentiation of adult human progenitor bone marrow stromal cells. Also, the direct inflammatory potential of silkworm silk was studied using an in vitro system [40]. The authors claimed that their silk fibers were mostly immunologically inert in short and long term culture with murine macrophage cells. 

Synthetic Spider Silk Fibers Natural vs Artificial Spinning Strategies 174... 

It is now clear from the study of silk fiber formation in lepidoptera and spiders (Akai, 1998 Iizuka, 1966 Kerkam et aL, 1991 Knight and... 

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