Effect of tourmaline superfine powder additive on mechanical properties of silkworm fiber

Abstract

• Superfine tourmaline powders of low concentration played a positive role in the growth of silkworm and cocoon quality. • Tourmaline powders absorbed into silkworm improved the mechanical properties of silk. • Tourmaline might provide a wide application prospect in the production of functional silk. This study aims at analyzing the effect of adding superfine tourmaline (Tml) powders on the growth of silkworms, the quality of cocoon, and the mechanical properties of silk fiber. Superfine tourmaline powders and TiO 2 nanoparticles (NPs) were fed to silkworms, respectively, and then the survival and proliferation rate, the weight of cocoon and shells, and the mechanic qualities of silk fiber were investigated. Experimental results demonstrated that the superfine tourmaline powders had no adverse impact on the growth and the survival rate of silkworm. The stress and strain of silk fiber, to which 10mg of Tml were added, increased up to 510.6±48 MPa and 21±2.1%, respectively, which improved by 32.3% and 27.4% on average. Through the analysis of Fourier transforms infrared spectra (FTIR), it has been confirmed that such result was attributable to the increase of random coil/α-helix structure in the silk fiber structure. The research will be of certain significance in simplifying the production mode of silk fiber with more functions by using the radiating far-infrared rays and the spontaneous polarization effect of tourmaline.