Evaluation of Tensile Properties of Spider Silk Cocoon Yarn in Different Humidity Conditions

Abstract

Kuwana et al., (2014) reported the breaking stress and breaking strain of spider silk (C515-SpA1x2) respectively as 13.5% and 42.5% higher than those of native silk (C515). However, C515-SpA1x2 produced around 10 years ago exhibited a marked decrease in its tensile properties. After several treatments applied to silk, moisture was observed to play a role in the change of tensile properties of C515-SpA1x2. Furthermore, after immersion in 99.5% ethanol, the difference in slope between C515 and C515-SpA1x2 in the plastic deformation region widened. Both treatments were regarded as strongly affecting the amorphous region. This result indicates that the spider proteins are expressed disproportionately in the amorphous region.