Effects of silkworm variety on the mechanical and structural properties of silk

The mechanical properties of silk, including stress and strain, play a key role in many emerging fields. In this study, seven types of silkworm (Bombyx mori) silk were studied to verify the effects of silkworm variety on the mechanical properties of silk, as well as diameter, morphology and structure. Results demonstrated that the physical properties and chemical structure of silk were highly dependent upon silkworm variety, although the FTIR spectra and XRD curves were very similar. Due to the high content of silk Ι (α-helix/random coil), three kinds of silk (7532 × 781, 9Fu × 7Xiang and A1) had superior tensile strengths of 644.05, 579.85, and 652.59 MPa, and strains of 23.29, 19.98, and 16.65%, which were considerably higher than those of the other four varieties. Yuncan Ι silk had a relatively higher silk production with a weaker tensile strength. Our study is first to illustrate the relationship among silkworm variety, silk mechanical properties, and silk chemical structure. In addition, this study might provide a useful reference to cultivate new silkworm variety for producing silk fiber with higher quality.