Dragline silk mechanical properties

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. 

As to fibers, it was reported that the inferior mechanical properties of silk from cocoons compared to spider silk result from the silkworm spinning process. If silkworm silk is processed at a constant pulling speed rather than constant force pulling, it possesses excellent properties, approaching the spider dragline silk (Shao and Vollrath, 2002). This suggests that the silkworm silk has the potential to produce better fibers, and the regenerated fibroin, which is easy to harvest, has the possibility to be fabricated into a reconstituted super-fiber. 

Dragline spider silk has aroused considerable interest due to its excellent mechanical properties, for example stability, elasticity and low weight. A. Bram and co-workers (ESRF) have succeeded in recording X-ray diffraction patterns from a single spider dragline of less than 10 pm diameter(Figure 3(b)). These results allow the elastic properties of the fibres to be linked to the molecular architecture of the polymer chains. 

Comparison of Mechanical Properties of Common Silks (Silkworm and Spider Dragline) to Several Types of Biomaterial Fibers and Tissues Commonly Used Today... 

It is uncertain whether spider silks show actual characteristic properties even though many researchers have been interested in the physicochemical properties of spider silks.This is mainly due to the difficulty in obtaining sufficient numbers of dragline samples appropriate for thermal, optical and aging experiments, in preparing the samples with no mechanical hysteresis and in measuring the mechanical properties because the silk samples are very thin. 

The mechanical properties of spider dragline silk are especially well-studied, mostly for the common garden spider Araneus diadematus and... 

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