Unexpected high toughness of Samia cynthia ricini silk gut

• Published in: Soft matter 2022-07, Vol.18 (26), p.4973-4982
• Main Authors: Aznar-Cervantes, Salvador D., Cenis, José Luis, Lozano-Picazo, Paloma, Bruno, Augusto Luis, Pagán, Ana, Ruiz-León, Yolanda, Candel, María José, González-Nieto, Daniel, Rojo, Francisco Javier, Elices, Manuel, Guinea, Gustavo Víctor, Pérez-Rigueiro, José
• Format: Article
• Language: English
• Subjects: Elastomers; Fibers; Infrared spectroscopy; Load history; Mechanical properties; Microstructure; Samia cynthia ricini; Scanning electron microscopy; Silk; Silk gland; Silkworms; X-ray diffraction
• ISSN: 1744-683X; 1744-6848
• DOI: 10.1039/d2sm00340f

Silk gut fibers were produced from the silkworm Samia cynthia ricini silk glands by the usual procedure of immersion in a mildly acidic solution and subsequent stretching. The morphology of the silk guts was assessed by scanning electron microscopy, and their microstructure was assessed by infrared spectroscopy and X-ray diffraction. It was found that both naturally spun and Samia silk guts share a common semicrystalline microstructure. The mechanical characterization of the silk guts revealed that these fibers show an elastomeric behavior when tested in water, and exhibit a genuine ground state to which the fiber may revert independently of its previous loading history. In spite of its large cross-sectional area compared with naturally spun silk fibers, Samia silk guts show values of work to fracture up to 160 MJ m −3 , much larger than those of most of their natural counterparts, and establish a new record value for this parameter in silk guts.