Enhanced mechanical qualities of sericin‐removed silk by direct feeding of silkworms with cellulose nanofiber

Abstract

AbstractRecently, the modification of silkworm silk fibers (SFs) by adding fillers has been investigated. Previously, we have reported that SFs obtained from silkworms fed diets supplemented with 5 wt.% cellulose nanofiber (CNF) and whose surface was covered with sericin exhibited excellent tensile properties. On the other hand, to use SF in silk products, the sericin must be removed, and it is necessary to ensure that CNF‐enriched silkworm SFs with the sericin removed (i.e., fibroin) exhibit high tensile properties. Therefore, this study evaluated the tensile properties of sericin‐removed SF obtained from silkworms fed a CNF diet. The results showed that the average CNF with SF—near 7.5 wt.% exhibited high mechanical properties. Adding CNF to the silkworm diet did not affect their growth and cocoon yield. The analysis of the SF microstructure confirmed that CNF is a fibrous material on the surface of fibroin. Kelly‐Tyson's equation suggested that almost all of the CNF in fibroin contributed to the increased tensile strength.