Crystalline states of spider silk changes with humidity and strain rates

March 10, 2020

A guideline for designing tough artificial spider silk

A joint group of researchers from RIKEN CSRS, the Japan Synchrotron Radiation Research Institute (JASRI), and University of Malaya have found that toughness of spider silk enhances under the humidity of its habitat and when it stretches at a speed close to that of flying insect prey.

The joint research group collected dragline silk (spider silk) of wild Nephila clavata, which serves as a lifeline, and assessed how the humidity and the strain rate of spider silk affected the structure and mechanical properties of the draglines. It was found that energy absorption (toughness) of spider silk increases under mild humidity, or when the stretching speed is close to the flying speed of prey insects when they are caught by spider silk. The increase in toughness may be due to the load, which is imparted more equally on the entire length of silk when it stretches at a high speed. The team also revealed the mechanism in which the structure of spider silk changes with humidity and strain rates.

Results of this research will be useful to establish a guideline for designing artificial spider silk, which has been attracting attention as a next-generation material replacing existing petroleumbased plastics due to its light-weight and high-strength properties as well as its biodegradability and low cytotoxicity. Artificial spider silk is also expected to be applied in medical uses and space industry.

Original article
Communications Materials doi:10.1038/s43246-020-0011-8
K. Yazawa, A. D. Malay, H. Masunaga, Y. Norma-Rashid, K. Numata,
"Simultaneous effect of strain rate and humidity on the structure and mechanical behavior of spider silk".
Keiji Numata
Team Leader
Biomacromolecules Research Team