Tensile mechanical property evaluation of natural and epoxide-treated silk fibers (original) (raw)

Silkworm cocoon silk and spider major ampullate (drag line) silk exhibit macroscopic tensile properties that, while impressive in the context of polymer fibers, are highly variable. T h e variability is linked t o the cross-sectional geometry being nonuniform: silk fiber cross section changes significantly over distances t h a t are small compared t o t h e scale on which diameters are averaged by typical characterization techniques. This characteristic must be taken into account when evaluating chemical treatments (in the present case infiltrating with crosslinkable epoxide) that are aimed a t improving strength or stiffness. The magnitude of any change in mechanical property must be considered in relation to the spread in values recorded prior to treatment. An apparent improvement in the mean value of a tensile property may turn out to be statistically insignificant when compared to the standard deviations associated with those data.